The hidden hazard in every sip: tackling microplastics in drinking water through detection and mitigation

Abstract

Microplastics (MPs), recognized as contaminants of emerging concern, have become global in drinking water systems, posing increasing risks to food safety, public health, and environmental sustainability. As drinking water represents a major route of human exposure, understanding the occurrence, detection, and mitigation of MPs is essential. This review comprehensively evaluates the predominant polymeric types of MPs detected in drinking water, including polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polyamide (PA), polystyrene (PS), and polyvinyl chloride (PVC), together with their major sources and formation pathways. The review critically compares the principles, advantages, and limitations of current analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), micro-FTIR (μFTIR), Raman and micro-Raman (μRaman) spectroscopy, scanning electron microscopy (SEM), chemical imaging, pyrolysis gas chromatography–mass spectrometry (Py-GC–MS), and smartphone-based microscopy. Evidence from worldwide studies demonstrates that MPs are consistently detected in bottled, tap, and groundwater, with substantial variations in abundance, size, morphology, and polymer composition depending on water sources, treatment processes, and distribution systems. Conventional and emerging mitigation approaches, including coagulation–flocculation, membrane filtration, boiling, pulse clarification, and magnetic oxide-based composites, are also critically assessed with respect to their removal efficiencies and practical limitations. Furthermore, the review identifies key research gaps, including the lack of standardized analytical protocols, limited understanding of nanoplastics, and insufficient knowledge regarding long-term human health effects. By integrating current evidence on occurrence, analytical methodologies, health implications, and mitigation strategies, this review provides a comprehensive framework to support standardized monitoring and the development of effective approaches for improving drinking water quality and protecting human health.

Highlights

• •The contamination of water poses a major threat to public health.
• •Microplastics have been detected in every country and are a hidden cause of serious health concerns.
• •Polyethylene, polyamide, polystyrene, and polyvinyl chloride are the primary microplastics.
• •μFTIR, μRaman spectroscopy and GC–MS can be used to identify microplastics.
• •Pulse clarifiers, and magnetic oxide composites can be used to mitigate microplastics.

1. Introduction

Less than 10% of the 400 million tons of plastic produced each year is recycled. Plastics offer significant social benefits due to their extensive use in everyday life and their low cost. They not only promote product preservation and consumer convenience but are particularly advantageous in the packaging industry (Amenábar Cristi et al., 2020; Soares et al., 2021). The COVID-19 pandemic has resulted in a rise in delivery services, as well as the use of masks and gloves (that are disposable), further exacerbating the excessive use of plastic waste. This marks a significant setback in this regard, as it was expected that plastic consumption would decrease before the pandemic. Major packaging companies were making progress in revising their policies to promote the green economy and appeal to younger consumers (Arienzo et al., 2021).

Water is a vital requirement for all human, industrial, and agricultural activities, as well as for the biological processes of all animals, ensuring the sustenance of life on Earth (Eltaweil et al., 2022). Groundwater is becoming a significant concern for towns and cities worldwide. There has been a marked global increase in the dependence on groundwater for agriculture, industrial, and domestic purposes (Das et al., 2021; Q. Zhang et al., 2021). The need for groundwater for drinking purposes has risen alongside global population growth. Currently, about 1/3rd of the world's population relies on groundwater for drinking. Many regions, particularly developing countries, face substantial challenges in accessing clean drinking water. It is noted that contamination in water not only impacts the quality of water but also hinders social prosperity, economic development, and human health (Islam et al., 2022; Kumar et al., 2022; Shaibur & Das, 2022).

MPs are defined by the European Chemicals Agency and the U.S. National Oceanic and Atmospheric Administration (NOAA) as plastic fragments <5 mm in length. The United Nations Environment Programme (UNEP) describes them as solid particles of plastic, insoluble in water, and no larger than 5 mm. According to the ISO/TR 21960:2020 standard, the International Organization for Standardization (ISO) ISO/TC 61 (Plastics)/SC 14 (Environmental Aspects) defines MPs as solid particles of plastic, water-insoluble, with sizes ranging between 1 and 1000 μm (ISO, 2020). The MPs originate from two primary sources: direct generation and secondary generation. Secondary MPs form when larger plastic debris breaks down due to chemical and physical processes in the environment. The production of primary MPs, such as microbeads, has been banned due to their substantial contribution to environmental pollution. However, plastics already discarded in the natural environment may continue to generate secondary MPs (Gálvez-Blanca et al., 2024; Mitrano & Wohlleben, 2020). Even at low concentrations of 10 μg/mL, MPs can have detrimental effects on animals and humans, such as male infertility, cytotoxicity, immune responses, oxidative stress, disruption of barrier functions, and genotoxicity (Tang et al., 2024). In marine animals, ingestion of MPs alters gastrointestinal physiology and leads to immune suppression, cytotoxicity, oxidative stress, changes in gene expression, and inhibited growth (Enyoh et al., 2020). The bad effects of MPs on human health are described in Fig. 1.

Fig. 1.

Bad effects of MPs on human health

Previous review articles have primarily focused on the environmental occurrence of microplastics, their ecological impacts, human health risks, or their presence in aquatic ecosystems. Although these studies provide valuable insights, a comprehensive review dedicated specifically to drinking water that critically integrates the occurrence, polymeric characteristics, analytical detection techniques, mitigation strategies, and existing research gaps remains limited. Moreover, rapid advancements in analytical technologies and increasing reports of microplastic contamination in drinking water distribution systems necessitate an updated synthesis of the available evidence.

This review addresses these gaps by providing a comprehensive and critical evaluation of the major polymeric types of microplastics detected in drinking water, their sources and formation pathways, and the strengths and limitations of current analytical methods, including FTIR, μFTIR, μRaman spectroscopy, SEM, chemical imaging, Py-GC–MS, and smartphone-based microscopy. It critically compares conventional and emerging mitigation strategies based on their effectiveness, applicability, and practical limitations. This identifies key challenges, including the lack of standardized analytical protocols, limited understanding of nanoplastics, and uncertainties regarding long-term human health effects, while proposing future research priorities to support standardized monitoring and the development of safer drinking water systems.

2. Microplastics generation and pathways into drinking water

Microplastics (MPs) can enter drinking-water systems through both direct and indirect pathways. Secondary MPs are generated through the fragmentation and weathering of larger plastic materials under the influence of ultraviolet radiation, oxidation, mechanical abrasion, and temperature fluctuations, whereas primary MPs may be released directly from plastic-containing products and anthropogenic activities. These particles can subsequently reach drinking-water sources through wastewater discharge, surface runoff, atmospheric deposition, and transport within rivers, lakes, reservoirs, and groundwater. Their persistence and mobility are influenced by polymer type, particle size, density, morphology, and surface characteristics, which determine their transport, settling, resuspension, and interactions with suspended solids and natural organic matter.

The drinking-water treatment and distribution stages can further influence the occurrence and characteristics of MPs. Conventional processes such as coagulation, flocculation, sedimentation, and filtration can remove a substantial proportion of MPs, particularly larger particles; however, removal efficiency varies with particle characteristics and treatment conditions. MPs may also be introduced or released during transportation through distribution pipes, fittings, storage tanks, and other polymer-containing components as a result of mechanical abrasion, aging, pressure, disinfectant exposure, and surface deterioration. Therefore, MP concentrations at the point of consumption may differ from those measured in source or treated water. Bottled drinking water represents an additional pathway, as particles may originate from plastic bottles, caps, packaging components, handling, and storage conditions.

Once present in drinking-water systems, MPs generally exhibit considerable persistence because common polymers are resistant to rapid biodegradation. Nevertheless, environmental and operational stresses, including UV exposure, oxidation, mechanical abrasion, and temperature changes, can alter their surface properties and promote cracking and fragmentation. Such degradation does not necessarily eliminate MPs but may produce progressively smaller particles, including nanoplastics, which are more difficult to detect and characterize. Thus, the drinking-water MP pathway should be considered as a continuum from plastic production and environmental release to water-source contamination, treatment, distribution, packaging, and final consumption, with MPs potentially being introduced, removed, transformed, or fragmented at different stages.

3. Main polymeric types of MPs

MPs found in drinking water are derived predominantly from commonly used synthetic polymers, including polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polyamide (PA). These polymers differ in density, crystallinity, hydrophobicity, chemical structure, and resistance to environmental degradation, which influence their transport, persistence, fragmentation, and behavior during water treatment. PE and PP are widely used in packaging, containers, pipes, and other consumer products, whereas PET is extensively associated with beverage bottles and packaging. PS is commonly used in food packaging and insulation, PVC is widely used in pipes and construction materials, and PA is frequently associated with textiles and other manufactured products. Consequently, the polymer composition of MPs in drinking water can provide useful information about their potential sources and environmental pathways.

3.1. Polyethylene (PE)

PE is highly inert and resistant to degradation, making it challenging to break down in the environment, even after being concealed in a landfill for many years. When a PE piece was stored in soggy soil for 12–32 years, it exhibited only limited degradation and minimal weight loss. This recalcitrance is attributed to PE's high molecular weight, crystallinity, hydrophobic nature (due to its linear carbon atom backbone), and insolubility in water (Nisticò, 2020). Research has been carried out on the biodegradation of PE types, including low-density polyethylene (LDPE) and high-density polyethylene (HDPE). LDPE is formed by polymerizing ethylene under high pressure, resulting in its low density due to the presence of branched chains. While LDPE is chemically inactive at room temperature, it can be slowly degraded by certain solvents and strong oxidizing agents, which may cause it to soften or swell. It remains stable for a short period at 95 °C, but it can endure prolonged use at 80 °C. LDPE's crystallinity, ranging from 50 to 60%, contributes to its tensile strength, tear strength, opacity, stiffness, chemical resistance, and flexibility, even at low temperatures (Y. Zhang et al., 2022). LDPE comes in two types: branched low-density polyethylene (BLDPE) and linear low-density polyethylene (LLDPE), each differing in surface functional group availability, degree of branching, and density. LDPE films are transparent, non-toxic, and odorless, with enhanced ductility, heat-sealing properties, and water vapor permeability. These characteristics make LDPE widely used in manufacturing trays, plastic bags, and packaging for both food and non-food items. LDPE is utilized in polyhouse construction, agricultural field mulching, and as a coating for textiles, paper, and other polymers (Baur et al., 2023). PE is responsible for 97% of total agricultural byproduct vinyl, with approximately 200,000 tons of LDPE making up 64% of all agricultural byproduct vinyl. HDPE is a PE thermoplastic formed through a catalytic process and characterized by minimal branching. This results in stronger intermolecular forces and high tensile strength compared to LDPE. The greater density of HDPE provides enhanced firmness due to shorter bond lengths and more dense packaging. Its opacity, hardness, and ability to withstand elevated temperatures (up to 120 °C) make HDPE extensively used in various industrial and everyday applications, including the manufacture of carry bags, milk jugs, detergent bottles, margarine tubs, garbage containers, and water pipes (Ghatge et al., 2020).

3.2. Polyethylene terephthalate (PET)

PET, commonly known by the acronym PETE, or the recycling code #1, is one of the most broadly used thermoplastic polymers in the market. PET belongs to the polyester family, a large group of polymers characterized by the presence of esters in their main molecular chains. In addition to PET, the polyester family comprises other polyesters, both naturally occurring and oil-derived, such as the polyhydroxyalkanoates (PHAs) subgroup, which is produced through bacterial fermentative processes (Benyathiar et al., 2022). In a traditional oil refinery, ethylene glycol (EG) and terephthalic acid or preferably its dimethyl ester (DMT) are derived from crude oil and used in the production of PET. The production process for PET involves prepolymerization, which is independent of the monomer source, followed by step-growth polycondensation. Depending on the monomer used, this process can be classified as either esterification (when using terephthalic acid) or transesterification (when using DMT). Specifically, terephthalic acid is insoluble in EG under moderate pressures (approximately 3–6 bar) and high temperatures (around 250 °C), making the pre-polymerization step comprising the diacid terephthalic acid and the diol EG (esterification, path a) a heterogeneous reaction. The solubilization of terephthalic acid in EG is enhanced by the high temperature. Additionally, since the diacid functionalities naturally catalyze the esterification reaction with the diol, no external catalysts are required for the process (Sarda et al., 2022). In contrast, the process comprising DMT and EG requires a transesterification reaction conducted at a lower temperature (approximately 150–200 °C) with a catalyst present in a small amount (less than 0.5% by weight) and an excess of EG. The chosen catalyst naturally holds antimony. In this method, the byproduct, methanol, must be removed through distillation to shift the equilibrium reaction toward the formation of the desired prepolymer, bis-(2-hydroxyethyl) terephthalate. In the second step, the prepolymer undergoes polycondensation by being heated to an elevated temperature (around 300 °C) under vacuum. Antimony oxide (Sb₂O₃) serves as a catalyst to facilitate the removal of ethylene EG released during the condensation process. Maintaining an equimolar ratio between the two monomers is essential to increase the degree of polymerization in step-growth polycondensation reactions for linear polymers. In practice, any stoichiometric excess of one monomer over the other significantly decreases the degree of polymerization (Nisticò, 2020).

3.3. Polypropylene (PP)

PP is a profitable thermoplastic polymer known for its exceptional properties, including fire resistance, ease of processing, high heat distortion temperature, and dimensional steadiness. Accounting for 16% of the worldwide plastics market, PP is extensively used in the production of consumer goods, including plastic packaging (Shirvanimoghaddam et al., 2021). The capability to develop new products using PP, combined with its mechanical and thermal properties, enhances the significance of blending PP with both natural and synthetic fibers. This versatility makes such combinations increasingly valuable. Research has shown that during the recycling of PP, the occurrence of various biodegradable polymers can be noticed as impurities. These impurities can adversely impact the mechanical and thermal characteristics of the recycled PP, as well as the overall recycling process involving biopolymers. This is crucial for the final applications of PP-based materials. PP can be mixed with various biodegradable polymers, such as thermoplastic starch (TPS) and polylactic acid (PLA). However, additional methods are necessary to remove these impurities from recycled PP to prevent negative environmental impacts. Recycling PP with such impurities is significantly more challenging than recycling pure PP (Wróbel et al., 2023). PP can be categorized into 3 groups based on its chemical and physical characteristics. Homopolymer propylene (HPP) consists solely of propylene monomers and is found in a semi-crystalline solid arrangement. Random copolymer propylene (RCP) incorporates ethylene as a co-monomer, with amounts ranged from 1% to 8%. Impact copolymer propylene (ICP), a type of HPP, includes an RCP phase with 45–65% ethylene. Among these, HPP is the most widely used in the plastic production industry. Market estimates suggest the approximate shares of these PP types are: RCP 5–10%, ICP 20–30%, and HPP 65–75% (Alsabri et al., 2022).

3.4. Polyamide (PA)

PAs are a prominent group of high-performance polymers used across different industries, including pipelines, automotive, textile, and medical fields. They are typically produced either from amino acids (AB-type) or by condensing diacids and diamines to form AABB-type polymers. Alternatively, PAs can be synthesized through the ring-opening polymerization (ROP) of lactams. The most well-known lactam used as a monomer is caprolactam, a seven-membered cyclic amide that polymerizes to produce PA-6. Traditionally, caprolactam is manufactured from cyclohexane, which is derived from fossil fuels through a process involving oxidation to cyclohexanone, formation of an oxime, and Beckmann rearrangement. Recently, bio-based methods have been developed to produce caprolactam from glucose and fructose via hydroxymethylfurfural (HMF) (Češarek et al., 2020). The depletion of fossil fuels and the environmental concerns associated with their use in plastics have led to increased interest in alternative monomer sources for polymers, particularly PAs. Bio-based PAs, such as PA1010, PA11, and PA410, illustrate that sustainable monomer sources can effectively replace fossil fuels. These PAs are non-chiral, linear condensation polymers derived from castor oil-based amino acids or diacids. Their development demonstrates the viability of bio-based resources as substitutes for traditional fossil-derived monomers (Stockmann et al., 2020).

3.5. Polystyrene (PS)

PS is an aromatic polymer produced by the polymerization of styrene monomers. Styrene, also known as vinylbenzene, is derived from ethylene and benzene. The large-scale production of PS involves the catalytic dehydrogenation of ethylbenzene, which produces styrene monomers. PS is a thermoplastic polymer known for its durability, high translucency, and ease of dyeing. As a solid material, PS is used in manufacturing products like CDs, toys, and toothbrushes. PS is used to produce styrofoam, a material with limited elasticity that is either expanded or melt-formed. Styrofoam is produced by rapidly heating PS pellets with a foaming agent and is widely used for food containers such as cups, plates, and trays. It is also employed for food storage and transport, packaging of different products, and the production of office supplies, clips, and toys (Yeung et al., 2021). PS exhibits moderate thermal stability. At temperatures below 200 °C, pure PS shows minimal degradation; however, traces of ethylbenzene, cumene, and styrene can be detected in the air. When exposed to temperatures above 330 °C, PS almost completely degrades, primarily releasing styrene monomer. The byproducts of PS's thermal breakdown are generally less toxic compared to those from other common natural and synthetic materials. The relatively low toxicity of PS is associated with the small amounts of degradation products, such as styrene, that is emitted from PS-containing products (Kik et al., 2020).

3.6. Polyvinyl chloride (PVC)

PVC is one of the most extensively used plastics globally. It is known for its durability and resistance to corrosion, making it valuable in various sectors including healthcare, electrical, packaging, transportation, construction, building, and more. Unlike other plastics such as PP and PET, PVC is challenging to recycle and is often disposed of immediately after use. Improper handling of PVC waste can lead to the formation of several environmental pollutants (Yan et al., 2021). Firstly, dioxins, which are highly toxic persistent organic pollutants (POPs), can be generated during the production, recycling, and incineration of PVC due to its chlorine content. Secondly, the manufacturing of functional PVC materials often involves the use of hazardous chemicals as additives, such as flame retardants, plasticizers, and lead-based stabilizers. Flame retardants such as tris-(2-chloroethyl)-phosphate (TCEP), tris-(2-chloropropyl)-phosphate (TCPP), and tris(1,3-dichloro-2-propyl)-phosphate (TDCPP) found in certain PVC materials can be highly toxic. They pose significant risks to human reproduction, development, and respiratory health, and are associated with cancer, birth defects, chromosomal abnormalities, and other health issues. To advance PVC recycling and reduce environmental pollution, it is crucial to understand the flow, stock, waste, and recycling patterns of PVC, as well as to examine future trends in PVC consumption (Liu et al., 2020). The chemical structures of the main polymeric types of MPs are given in Fig. 2.

Fig. 2.

Chemical structures of the main polymeric types of MPs.

4. Detection of MPs in drinking water

The detection and characterization of microplastics (MPs) in drinking water generally involve microscopic, spectroscopic, and thermoanalytical approaches. Microscopy-based methods, such as stereomicroscopy and scanning electron microscopy (SEM), identify and characterize suspected MPs according to their size, shape, color, and surface morphology, although microscopy alone cannot reliably confirm polymer identity. Fourier-transform infrared (FTIR) and micro-FTIR (μFTIR) spectroscopy identify polymers based on characteristic infrared absorption bands associated with molecular vibrations, whereas micro-Raman (μRaman) spectroscopy relies on characteristic Raman scattering signals produced by molecular bonds. These spectral fingerprints are compared with reference libraries to determine polymer composition. Combining μRaman with SEM provides complementary chemical and morphological information.

Other approaches provide alternative means of MP identification and quantification. Chemical imaging and laser direct infrared (LDIR) techniques combine spectroscopic signals with automated imaging to map and identify particles, while fluorescence staining uses the interaction of fluorescent dyes with polymeric particles followed by microscopic visualization. Pyrolysis–gas chromatography–mass spectrometry (Py-GC–MS) uses thermal decomposition of polymers followed by chromatographic separation and mass-spectral identification of characteristic degradation products, enabling polymer identification and mass-based quantification. Emerging smartphone-based microscopy systems use digital imaging and image-processing algorithms to recognize and quantify suspected particles. Thus, these methods differ in their analytical principles and the type of information obtained, and complementary techniques are often required to reliably determine MP abundance, size, morphology, and polymer composition in drinking water.

4.1. Use of Stereomicroscopy and FTIR analysis

Stereomicroscopy (also called a dissecting microscope) is a low-magnification optical imaging technique used for the visual identification and preliminary analysis of samples. Hossein et al. (2023) analyzed MPs in 10 different brands of drinking water by using a stereomicroscope and FTIR techniques. The outcomes indicated the presence of MPs in every brand of water ranging from 14 ± 6.8 to 56 ± 23 particles/L with an average of 35 ± 19 particles/L. The MPs observed under study were in the shapes of beads, films, fragments, and fibers. The fiber shape was most dominant as present in about 90% of the samples. The size of MPs was <0.5 mm. FTIR analysis revealed the presence of PET, ethylene vinyl acetate, HDPE, and LDPE in all the samples where HDPE and LDPE were most dominant. Paray et al. (2024) used stereomicroscope and FTIR analysis to investigate the MPs contamination in groundwater from 6 coastal districts of Bangladesh. All the samples collected from the sampling stations contain MPs in them ranging from 4 to 75 items/L with an average of 24.63 ± 16.13 items/L. 97.6% of the MPs were fiber-shaped that were originated because of fabric disintegration during discarding of fishing nets, washing, drying, discarding of municipal waste and personal care items. Most of the MPs were composed of PE, LDPE, HDPE, ethylene vinyl acetate, and PET with size smaller than 0.5 mm. In another research, Bhola and Chakraborty (2024) examined MPs in 3 drinking reservoirs at the area of Ranchi in India by using stereomicroscope with a fluorescence adapter and FTIR analysis. The MPs were found in all 180 water samples ranging from 3699 to 6873 (count of MPs) with HDPE and PET as their chemical types. Most of the MPs were fiber-shaped, fragments, foams, and films with size below 0.5 mm.

Pérez-Guevara et al. (2022) performed polymeric identification of the MPs in 63 drinking water samples taken from decentralized refill kiosks in the metropolitan area of Mexico City by using FTIR spectroscopy combined with attenuated total reflectance (ATR). The MPs were found in all the drinking water samples ranging from 11 to 860 MPs/L and mainly composed of cellophane, polyacetal, vinyl polymers, PAs, and PET. Most of the MPs were fiber-shaped (65%), fragment-shaped (28%), and films (7%) and 75% of the MPs were smaller than 300 μm. Residents of Mexico City were estimated to ingest 42 MPs/L, with an annual exposure of around 1.47 × 10^4 MPs per adult and 6.73 × 10^3 MPs per child. Wu et al. (2022) identified MPs in shallow groundwater taken from Tianjin district in northern China by using FTIR spectroscopy. The samples were collected from 10 sampling sites and MPs were found in all of them ranging from 17.0 ± 2.16 to 44.0 ± 1.63 n/L. Most of MPs were fiber-shaped (44.74%) and 73.10% of the MPs were smaller than 200 μm. The chemical types identified were PS, PE, and PET. In another study, Oni and Sanni (2022) collected drinking water from Lagos Island located in Nigeria, added hydrogen peroxide in it and filtered it by using a polytetrafluoroethylene membrane. After that, FTIR analysis was performed to analyze the MPs. The results indicated 206 to 1691 items/m³ of MPs in drinking water sample and 9 to 47 items/kg in sediments. PE was the most predominant (61.9%) microplastic found and most of the MPs were present in the form of fragments (73.02%) with the size range of 0.02 to 0.5 mm.

4.2. Use of μ-FTIR spectroscopy

μ-FTIR analysis is a specialized technique used to identify and characterize materials, particularly at a microscopic level, by measuring how they absorb infrared light. It combines microscopy with FTIR spectroscopy, allowing for the examination of small sample areas, often less than 10 μm in size. Shi et al. (2022) used μ-FTIR spectroscopy to detect MPs in 81 groundwater samples taken from drinking-water source area at northern China. MPs were found in 100% of the samples with abundance ranging from 4 n/L to 72 n/L with an average of 29 n/L. The polymers of the MPs identified were PS, PVC, PE, and PA. Zhou et al. (2023) described that the abundance of MPs was increased when water is transported to the homes through plastic pipes from the water treatment plants after analyzing the MPs from the rural drinking water systems of Chongqing city of China by using μFTIR spectroscopy. The results showed that water treatment plants limit the number of MPs in the drinking water but when it comes to the tap water at homes, the levels were increased to 1.4 particles/L. The chemical types of the MPs detected were PE and PET with 0.5 mm to 1 μm in size. Almaiman et al. (2021) collected 30 water samples comprising of tap water, plastic-bottled water, and glass-bottled water from 5 different regions of Saudi Arabia and investigated for MPs by using μFTIR technique. The MPs were present in 17 samples out of 30 with an average range of 1.9 pcs/L to 4.7 pcs/L. The particle size of MPs was ranged from 25 to 500 μm. The main chemical types identified were PS, PE, and PET. Daily microplastic exposure was estimated at 0.1–0.2 pcs/kg bw for average water intake and 1.7–1.9 pcs/kg bw for high water consumers. In another research, Jung et al. (2022) investigated drinking water treatment plants located in Busan city of South Korea for the identification of MPs by using μFTIR technique. Monthly analysis was carried out and the MPs were detected in size range of above 20 μm with an annual average of 1.87 to 2.65 particles/L. The predominant polymeric compositions were PE and PET.

Gálvez-Blanca et al. (2024) identified MPs in Spanish bottled drinking water by using μFTIR analysis. The samples were taken from 1.5 L PET bottles of 5 leading brands in Spain. The average concentration of MPs was 1.61 μg/L with average size of 93 μm and their main chemical types were white and transparent PE and polyesters. Shen et al. (2021) investigated the occurrence of MPs in water samples collected from household tap water, treated water, and freshwater bodies located in Changsha, China by using μFTIR technique. The tap water had 267–404 (mean = 343.5), treated water had 338–400 (mean = 351.9), and fresh water had 2173–3998 (mean = 2753) particles L⁻¹ of MPs in them with PE terephthalate, PE, and PE as the most predominant chemical types. The 70% of MPs were fragment and fiber shaped. In another research, Semmouri et al. (2022) analyzed drinking water for the identification of MPs (in the range of 25 to 1000 μm) after collection from 9 treatment plants and 9 taps located in Flanders, Belgium by using μFTIR spectroscopy. The results showed 0.02 ± 0.03 MPs/L of MPs in the samples of drinking water treatment plants and 0.01 ± 0.02 MPs/L in the tap water samples. The most common chemical types identified were PET and PE.

4.3. Use of μ-Raman spectroscopy

μ-Raman spectroscopy is a powerful analytical method that combines Raman spectroscopy with optical microscopy to evaluate the molecular composition of small sample areas, often at the micron scale. It is used to study the vibrational, rotational, and other low-frequency modes of molecules in materials, providing detailed information about their chemical composition and structure (Di et al., 2019). Weber et al. (2021) collected drinking water from various locations of Rüsselsheim city of Germany including collection from consumption taps, transfer stations, and house connections. The water samples in the volume range of 0.25 to 1.3 m³ were then filtered by a using stainless-steel membrane and HCl was added in it. After that, μRaman spectroscopy was performed with a detection limit of 10 μm to identify MPs in the water samples. The results indicated no contamination of MPs in the water of the transfer station and house connections. However, one tap water sample had 113 ± 83 copper phthalocyanine particles per m³. Han et al. (2024) analyzed MPs in water samples collected from 2 treatment plants located in eastern China by using μRaman Spectrometer. Six different types of MPs were identified i.e., PET, PVC, PA, PS, PE, and PE in the size range of 2–5 μm. The PET was the most predominant among all other types. Di et al. (2019) identified MPs in the Danjiangkou Reservoir, China by using μRaman Spectroscopy. The MPs were present in all the sediment and water samples. The water samples had 467 to 15,017 n/m³ and the sediment samples had 15 to 40 n/kg wet weight of the MPs. The most common polymer was fiber-shaped PE with size smaller than 2 mm. In another investigation, Maurizi et al. (2023) examined MPs in groundwater from Denmark by using μFTIR and μRaman spectroscopy. μFTIR was unable to detect MPs contamination because of leakage from plastic components while μRaman detected those MPs. The MPs removal efficiency was higher when analyzed from μFTIR (counts: 78.14 ± 49.70%, mass: 98.73 ± 11.10%) and less fluctuating than when using μRaman (counts: 43.2%, mass: 75.1%). Both techniques showed ∼80% removal efficiency of MPs with size greater than >6.6 μm. Relying on only μFTIR led to underestimating the MPs content, as most of the MPs in the size range 1–50 μm was missed.

4.4. Use of μ-Raman with Scanning Electron Microscopy (SEM)

Adib et al. (2021) identified MPs in 3 conventional drinking water treatment plants located in the Tehran city of Iran by using SEM and μ-Raman spectroscopy with focus on particles smaller than 1 μm. The MPs were present in all the samples under study with amounts ranging from 1996 ± 268 to 2808 ± 80 MPs/L in raw water and from 971 ± 103 to 1401 ± 86 MPs/L in treated water. The chemical types identified were PE, PE terephthalate, and PE which accounted for 53% of the particles in the form of fragments, spheres, and fibers. In another study, Taghipour et al. (2023) identified MPs from 4 reservoirs, 2 water treatment plants, and 10 consumption taps by using SEM, FTIR, and μRaman spectroscopy techniques in winter and spring at Zahedan city of Iran. In winter, MPs in raw water were ranged from 15.4 to 44.7 MP/m³ and in spring, it was 22 to 51.8 MP/m³. An investigation of before and after treatment plants, indicated the removal of 64% and 75% of the MPs. In consumption taps, the abundance of MPs was higher (75–400 MP/m³) as compared to the treatment plants and it indicated the more contamination from pipes and installations. PS is the most predominant chemical type of MPs identified under study.

4.5. Use of staining techniques

Mohan et al. (2023) analyzed the MPs in various brands of bottled water in the region of India using the FTIR and Nile red staining method. The FTIR evaluation revealed PA, PE, and PS in the samples in which PE was the most common. The Zebrafish embryos exposed to fluorescent-tagged PE MPs in the size range of 10–150 μm showed the accumulation of MPs in different body organs over time, increased downregulated antioxidative defense genes and ROS activity indicating concentration- and time-dependent toxicity. The outcomes suggested the potential negative health impacts on humans the MPs exposure and oxidative stress. In another research, Alonso-Vázquez et al. (2023) separated, quantified, and examined the MPs with size range of 0.1 to 5 mm in drinking water collected from 3 drinking water treatment plants by Raman spectroscopy and Epifluorescence microscopy in which iDye Pink and Nile Red were used to stain the MPs for fluorescence. The polyester was the main polymer identified under the study and Raman spectroscopy revealed the presence of microfibers of polyester in the drinking water. The drinking water plants helped to limit the contamination of MPs up to 89%.

4.6. Use of chemical imaging system

A Chemical Imaging System is an advanced analytical tool that combines spectroscopy (such as infrared or Raman spectroscopy) with imaging techniques to obtain both spatial and chemical information from a sample. The system captures images where each pixel contains a full spectrum, allowing for the visualization of the chemical composition across the surface of the sample. This makes it possible to map the distribution of various chemical compounds, including microplastics. Yang et al. (2023) determined MPs in drinking water collected from pipe scales of a water distribution system located in eastern China by using a self-operating chemical imaging system with laser infrared technology (8700 LDIR). The MPs were found in all the samples under study in a range of 1.74 to 20.88 MPs/L in tap water and 0.03 to 3.48 MPs/cm² in pipe scales. Small MPs with size less than 150 μm were mostly fiber-shaped and most predominant chemical types were PA and PET.

4.7. Use of GCMS

Gomiero et al. (2021) assessed MPs of size ≥1 μm by using pyrolysis gas chromatography–mass spectrometry sample's analysis (pyr-GCMS) after collecting the water samples from Norwegian urban area. Prior to pyrolysis, in-situ enzymatic and mild oxidizing driven sample preparation was done by using a modular filtering sampling device. Polyester, PA, and PE were found in frequent amounts in the range of 6.1 to 93.1 μg/m³ per sampling site. Raw water contained higher amounts of MPs as compared to the treated water samples (43% to 100% reduction of MPs as compared to the raw water). In another study, Kirstein et al. (2021) quantified the MPs in drinking water samples collected from distribution systems located in Sweden by using Py-GCMS and μFTIR imaging. The results indicated that most of the MPs were smaller than 150 μm and even 32% of the MPs were smaller than 20 μm. The average number of MPs/m³ analyzed in the whole drinking water distribution system within the week of sampling was, 174 ± 405 MPs/m³. It ranged from a minimum of zero MPs/m³ at the waterworks, to a maximum of 1219 MPs/m³ in one sample from the pumping station.

4.8. Screening of MPs by a smartphone microscopic system

Karki et al. (2024) devised an advanced method of MPs imaging and quantification especially those that have size as small as 20 μm by using a smartphone microscopic system. The main imaging component of the system was a spherical sapphire ball lens with a diameter of 4 mm, which was attached to a smartphone camera. Additionally, the sample needed to be pre-concentrated using a ZnCl₂ solution. For filtered distilled and deionized water samples (n = 9), the method achieved a spike recovery of 55.6% ± 9.7% and a limit of detection of 35 particles/L. The imaging performance of the microscopic system was found to be comparable to that of commercial bright field microscopes. The technique was subsequently applied to examine microplastic particles in water samples from commercial bottles and jars (n = 20). The particle counts in the jar samples ranged from 0 to 91, while those in the bottle samples ranged from 0 to 130. Both types of samples contained particles of various sizes and shapes. To further verify the presence of plastic material, FTIR spectra (n = 36) confirmed that 97% of the particles tested from the water samples were MPs. The detection of MPs in drinking water systems as evidenced by different regions of the world has been described in Table 1.

Table 1.

Detection of microplastics in drinking water as evidenced by different regions of the world.

Country/Region	Samples investigated under study	Identification techniques used	Amount/range of microplastics detected	Shapes/structures identified	Key findings	References
Bangladesh	50 samples from 10 brands of bottled mineral waters	Stereomicroscopic+ FTIR	14 to 56 particles/L	90% fibers, 7% fragments, and 3% films and microbeads	Brand 2 had the highest MPs and Brand 7 the lowest. Brand 4 had 98% fiber-shaped MPs. Transparent MPs were the most common at 64%, while yellow was the least at 0.5%. MPs under 0.5 mm were 64%. PETE and HDPE made up 25% of the MPs. Daily MP consumption was 2.63 particles per person.	(Hossain et al., 2023)
Ranchi, India	180 samples of surface water of Getalsud, Kanke dam, and Dhurwa dam reservoir	FTIR	Water samples (total count: 3699—6873) and water samples Kanke reservoir: 0.2–4 MP L−1 Getalsud reservoir: 0.1–5.3 MP L−1 Dhurwa reservoir: 0.2–2.3 MP L−1	Getalsud: Fragments (76.4%), fiber (19.35%), film (3.8%), and foam (0.5%) Kanke reservoir: fragment (59.71%), fiber (59.71%), foam (2.18%), and film (5.89%) Dhurwa reservoir: Fragment (82%), fiber (14%), film (2.1%), and foam (1.6%)	Among the six colors identified, transparent and blue were predominant. Foams were mostly white, films were transparent, and fragments were a mix of all colors. Of the eight polymers identified, PET and HDPE were most common.	(Bhola & Chakraborty, 2024)
China	200 mLdrinking water	NR stain+ SEM	17 to 315 MPs/mL	Rough chunks: chlorinated samples; melted flakes: heated samples; irregularly shaped fragments with sharp edges: freeze-thawed samples	Cracks in MPs were smaller than 80 nm in width.	(Yang et al., 2024)
German city	0.25–1.3 m3 drinking water sample range	Raman μ- spectroscopy	3 ± 14% (22–27 μm) and 89 ± 28% (45–53 μm) articles were recovered at one tap	Copper phthalocyanine microparticles	No microplastics found in the consumption taps. Copper phthalocyanine pigment detected in one tap, likely from pipes. Low blank values indicate effective prevention of contamination and method suitability for analyzing microplastics ≥10 μm	(Weber et al., 2021)
Changsha, China	Freshwater, treated water, and household tap water	Raman spectroscopy and μ-FTIR	Freshwater: 2173–3998 particles L−1 Treated water: 338–400 particles L−1 Tap water: 267–404 particles L−1	Fragments> raw water> fibers and spheres	More than 85% of MPs in all samples were 1–10 μm in size. Polyethylene had the highest concentration in both raw and treated water, at 26.8% and 24%, respectively. The polymer content showed no significant difference between tap and treated water.	(Shen et al., 2021)
Northern China	81 groundwater monitoring wells samples	Optical Microscope+ FTIR	4 n/L to 72 n/L	Fragments (86.9%) and fibers	Sampling site 77 had the highest MPs content. MPs of 20–50 μm were most common at 41.4%. Fragments made up 86.9% of the MPs, with 86.3% being transparent. PA polymers were the main component.	(Shi et al., 2022)
Mexico City metropolitan area	63 pay-to-fetch drinking-water refill kiosks drinking water samples	High-resolution SEM coupled with energy-dispersive X-ray spectroscopy+ FTIR in ATR	11 to 860 L−1	Fiber (65%), fragment (28%), and film (7%)	75% of MPs were under 300 μm, with 20–100 μm being most common (33.82%). PET was the main polymer (37.4%). 24% of samples had fewer than 20 MPs/L. Estimated dietary intake: 14,700 MPs per adult and 6730 MPs per child per year.	(Pérez-Guevara et al., 2022)
Six coastal districts of Bangladesh (Cox's Bazar, Chattogram, Feni, Noakhali, Chandpur and Patuakhali)	54 GW drinking water samples sourced from groundwater	Stereomicroscopy+ FTIR spectroscopy	Concentrations: 24.63 items/L Range: 4–75 items/L	Fibers (97.6%), films (1.8%), fragments (0.3%), micro beads (0.3%)	Detected MPs mostly contained PE polymers, of smaller size (less than 0.5 mm) and of transparent as well as of violet color. Each person was consuming 1.85 particles per day. Polymers-related health risk values were HDPE 39%, LDPE 31%, and EVA 17%.	(Paray et al., 2024)
Five regions in Saudi Arabia (Central, Western, Northern, Southern, Eastern)	30 drinking water samples (24 PET single-use bottled water and 2 glass bottles, 2 samples of water bottled in 18-L hard PC plastic container and 2 samples of tap water)	FTIR μ- spectroscopy	LB: 1.9 ± 4.7 pcs/L UB: − 4.67 ± 13.0 pcs/L	P PE > PS > PET	MPs were found in 17 samples, with 38% consisting of PE polymers. Daily intake was 0.1–0.2 pcs/kg bw/day, with no differences between genders. Consuming 4.5 L of bottled water resulted in 1.7–1.9 pcs/kg bw/day of MPs intake.	(Almaiman et al., 2021)
Busan, South Korea	Two sites on the Nakdong River, two lake reservoirs (raw water sources), and four corresponding drinking water treatment plants	μ-FTIR spectroscopy	Annual average number: River A: 2.65 particles/L River B: 2.48 particles/L Lake C: 2.46 particles/L Lake D: 1.87 particles/L	Polyethylene (PE)/polypropylene (PP) (> 60%) and polyethylene terephthalate (PET)/poly(methyl methacrylate) (PMMA) (20%), polyamide (<10%) and polystyrene (<10%)	MPs levels were higher in the river than in reservoirs from January to April and October to November, with minor changes from June to October. Pre-ozonation/sedimentation removed 70–80% of MPs and 81–88% of PE/PP.	(Jung et al., 2022)
Megacity in eastern China	Two drinking water treatment plants	μ -Raman spectrometer	Raw water≈ 4700 items/L Sedimentation TW ≈ 2700 items/L Sand filtration TW ≈ 1800 items/L GAC filtration TW ≈ 800 items/L Centrifugation TW ≈ 700 items/L	Six types of MPs i.e. polyethylene terephthalate, polyethylene, polypropylene, polystyrene, polyamide, and polyvinyl chloride were detected	Most MPs in natural water were 2–5 μm (35.8–41.2%) and PET (27.1–29.9%). Treatment reduced MPs by 72.7–83.0%, with 2–5 μm MPs (55.3–64.3%) and PE (27.7%) in treated water. Infants ingested 45.5–75.0 MPs/kg daily, twice as much as adults.	(Han et al., 2024)
South Africa	2 samples from the source water+ Four samples were taken at the two plants immediately following the treatment process, i.e., Potable 1a and 1b + Four samples were taken from the distribution network, namely MABO, GARAN, WELTE and PELIN in Gauteng	FTIR	Source water: 0.24 to 1.47 particles/L Immediately after treatment: 0.56 to 0.9 particles/L Distribution network: 0.26 to 0.88 particles/L	Fragment and a few as fiber	25–300 μm size of MPs was most predominant. MPs decreased significantly by applying treatments to drinking water. MPs polymer in the form of rubber were most abundant. While depending upon mass, EVA polymer showed the highest content of 54.97%.	(Swanepoel et al., 2023)
Danjiangkou Reservoir, China	20 L water	μ -Raman spectroscopy	467 to 15,017 n/m3	Water samples: Fiber (20.8% to 99.2%), fragment (20.8% to 99.2%), pellet (1.9% to 17.1%) and Styrofoam	MP detection was similar in Dan (1406 n/m3) and Han (1457 n/m3) reservoirs. MPs sized 0.5–1 mm ranged from 8.3 to 56.4%. Blue MPs were predominant (17–84.6%), and most MPs were PP polymer (44.9%).	(Di et al., 2019)
Czech Republic (Zlin and Maravain Silesian region)	four samples of drinking water	μ-FTIR	40 Particles	Fiber (47%; 19 pcs.), Particle (30%; 12 pcs.), Fragment (18%; 7 pcs.), and Film (5%; 2 pcs.)	Among the 11 colors detected, brown color (9) was abundant.	(Halfar et al., 2023)
Spanish	45 L of five top-selling five brands for each brand (225 L for all brands) Of 1.5 L poly(ethylene terephthalate) bottled drinking water	μ-FTIR	1.61 (1.10–2.88) μg/L 81 MP particles	29 fibers, 51 fragments, and 1 film	Brand 5 had the highest MPs. Most MPs were polyester (PES) with white and transparent colors. The smallest MP was a fiber with a 12.5 μm diameter and 104 μm length, while the largest was a PE fragment of the same size.	(Gálvez-Blanca et al., 2024)
Tianjin city of northern China	10 groundwater samples (Zhou River and near the Yuqiao Reservoir)	optical microscopy+ μ-FTIR	17 to 44 n/L J3, J4, J9, and J10 close to the gas station: 24 to 44 n/L J1, J5, J6, J7, and J8 near the factory area: 17 to 25 n/L J1, J4, J5, J6, J8, and J9) in the agricultural area: 27.5 n/L) Sampling sites near to residential areas: 29.7 n/L Sampling sites in a deep water well: 27 n/L	Fibrous (44.74%), fragments (20.02%) films (28.39%), and pellet (6.87%)	Site J4 had the highest MPs, while site J6 had the lowest. Blue MPs were most common at 31.02%. In agricultural areas, 48.44–72.22% of MPs were transparent or black. Most MPs (73.10%) were 10–200 μm in size. PET was the dominant polymer, making up 24.73% of the 73.60% total polymers.	(B. Wu et al., 2022)
Tehran, Iran	3 DWTPs samples fed from (Karaj and Kan River, Jajrud River, Lar Dam)	SEM+ μ-Raman spectroscopy	Raw Water: 1996 to 2808 MPs L−1 Treated Water: 971 to 1401 MPs L−1	Raw Water: fibers 51.1%, fragments 35.6%, spherical 13.3% Treated water: 39% fibers, 60% fragments, 5.3% spherical.	In treated water, fragments were the most common MP type. MPs sized 10 μm constituted 65–87%. Among 10 detected polymers, PP was 27.3% in raw and 24.8% in treated water.	(Adib et al., 2021)
Lagos, Nigeria	10 L Borehole Drinking Water samples from 11 locations	FTIR	206 to 1691 items m−3	73% fragments, 5% fibers, 6% pellets, 8.5% films, and 7.5% flakes	Site 4 had the highest MP detection, with 61.9% made of PP polymer. MPs sized 0.02–1.0 mm made up ≥75% of all MPs at all sites. MP levels were directly linked to industrial activity.	(Oni & Sanni, 2022)
Rural area in Chongqing in southwest China	Reservoir, (WTP, and tap water samples (1.5 L from each site)	FTIR spectroscopy+ SEM	Tap water: 1.4 particles/L Reservoir: 9.7 particles/L WTP: 12.2 particles/L	Fibers: 62–100% Reservoir water: 73% Rural WTP: 67%	The dietary intake of MPs was 1034 MPs/year for those consuming 2 L of water daily. MPs increased from reservoirs to water treatment plants (WTP) and from WTP to tap water. Predominantly, MPs were white, followed by blue, and measured less than 300 μm, with a significant portion under 60 μm. In reservoirs, PET (58%) and PP (33%) were most common, while PET and PE were predominant in WTP samples.	(Zhou et al., 2023)
Yangtze River region, China	200 L treated water	μ- Raman imaging microscope system	695.66 ± 39.32 n/L	Granular	In raw water, 98% of MPs were 5–20 μm, primarily PP (25%). Larger MPs (100 μm–5 mm) made up 47.6%, with vinyl being dominant (70.4%). In treated water, 99.94% of MPs were 5–20 μm, with PP as the main polymer (30%).	(J. Wu et al., 2022)
Eastern China	5 tap water and 16 pipe scale samples (30 L from each site)	LDIR automatic chemical imaging system	water samples: 1.74–20.88 MPs/L pipe scales samples: 0.03–3.48 MPs/cm2	11.4% Fibers in tap water 28.0% Fibers in pipe scales	Tap water had the highest MPs concentration at 20.88 MPs/L. MPs were mainly 150 μm in size (91.6%). Among 34 polymers, PET was most common in pipe scales (50%) and PA in tap water (70.3%). PA was found in all samples, followed by PU in 19 samples. Ultra-fine fibers dominated in pipe scales, while short fibers were prevalent in water.	(Yang et al., 2023)
Riobamba city, Ecuador	62 sampling points (Sources of water collection A–S = 20 samples; Reserves A–N = 15; Distribution network A–Q = 18; Hydrants A–I = 9)	Stereoscope	Sources B, C, and G = 3 to 2 field units/250 ml Reserves D, I, K, and N = 2–1 field units/250 ml Distribution networks F and N = 1 field units/250 ml	Fiber	Sources B, C, and G; reserves D, I, K, and N; distribution networks F and N; and hydrants C, D, and I constitute about 15, 26.66, 11.11, and 33% of the analyzed samples. Only 19 out of 62 samples exhibited MPs detection.	(Paredes et al., 2019)
Geneva, Switzerland	1000 and 1950 L of raw water, before and after sand filtration and after activated carbon filtration	IR spectroscopy	Raw water had 19.5–143.5 MPs/m3. Sand filtration reduced this to 0–11.4 MPs/m3, and 0–5.6 MPs/m3 without coagulant. Activated carbon filtration brought it down to 0–4 MPs/m3.	-PET and PP	89% of MPs were in untreated water, rising to 97% with coagulant. MPs were mainly 63–125 μm in raw water (77%). Sand filtration reduced this to 74.5% with coagulant and 92% without. PEVA was the main polymer, showing 36% in raw water, 74% after sand filtration, and 50% after activated carbon filtration. No significant difference was found with or without coagulant.	(Negrete Velasco et al., 2023)
Mangaluru, India	20 different brands of plastic water bottles (500 mL)	NR staining+ FTIR	5–70 particles	80% fragments, 20% fiber	MPs were of 23.83–353.24 μm size. PE was the predominant polymer in MPs.	(Mohan et al., 2023)
Baghdad City; Al-Fahama, Al- Fath Al-Mubin, Al-Dora, and Al-Madaen station; Iraq	(1 l per sample) from four drinking water treatment plants	Florescent microscope+ FTIR spectrophotometer	Raw water: 17–62 MPs/L Drinking water: 9–40 MPs/L	Fibers: Raw water: Al-Fahamah 91.6%; Al-Fath Al-Moubin 58.8% and Al-Doura 65.3% Drinking water: Al-Fahamah 66.6%; Al-Fath Al-Moubin 77.7%; Al-Doura, 52.5% and Al-Madaen station 40.0% Spherical: Raw water: Al-Madaen station 82.2%	Polymer detections were as follows: Al-Fath Al-Mubin station: Nylon and Polycarbonate in raw water; HDPE and PP in drinking water Al-Doura station: PS in raw water; PA in drinking water Al-Madaen station: PET in raw water; PET and PU in drinking water.	(Sultan et al., 2023)
Flanders (Belgium), an urbanized region in Europe	Groundwater (n = 3) and surface water sources (n = 4)	μFTIR spectroscopy	DWTPs – Essen, Egenhove and Gavers – 0 MPs L− 1 TW samples: 0.01 MPs L− 1	PET and PP	Daily intake of MPs was 0.02 MPs of Flemish people. Mostly MPs were of PET (40.74%) and PP (33.33%) polymers. Only Ghent source samples exhibited PVC and PE polymers. 44% of MPs were of 50–75 μm size having 140 μm length.	(Semmouri et al., 2022)
Zahedan, Iran	4 reservoirs (raw water), before and after two WTPs, and 10 CTs	FT-IR+ Raman micro-spectroscopy+ FE-SEM	Raw water Winter: 15.4 and 44.7 MP/m3 Spring: 22–51.8 MP/m3 Before and after WTP1 = 127.5 MP/m3 and 45 MP/m3 Before and after WTP2 = 77.5 MP/m3 and 20 MP/m3 Consumption taps CTa = 85–390 MP/m3 CTb = 75–400 MP/m3	Source No.1: fiber (46%), fragments (43.5%), foam (4.5%), and film (6%) Before WTPs: Fibers (<50%), fragment (>50%) After WTPs: Fiber and fragment = 50% CTs: Fragment (>60%) Fiber (<40%)	Spring had more MPs than winter. WTP1 and WTP2 removed 64% and 75% of MPs, respectively. PS polymers were common. Reservoir MPs were mostly 100–500 μm. Transparent MPs were most common at source 1, while blue dominated before WTPs and red after. In CTs, white and transparent MPs were prevalent. Daily MP intake was 0.16–15 MPs/kg bw for children and 0.07–5.7 MPs/kg bw/year for adults. MPs often had rough surfaces with pits.	(Taghipour et al., 2023)
–	20 L Danish groundwater-based waterworks drinking water	μFT-IR+ Raman micro-spectroscopy	μFTIR = 78.14% μRaman 43.2%	Fragments 79.3% + Fibers 20.7%	The human MP consumption detected by μFT-IR was 332 times lower than μRaman spectroscopy thus lost 1–50 μm MP intake. In inlet samples, MPs were mostly of size range 1–50 μm MP (upto 40%) while in outlet samples MPs were of 50–100 μm (up to 36.6%). By μFTIR, it was found that, MPs from inlet and outlet samples were made up of PVC (7.0–54.0%) and (0–84.7%), respectively. But μRaman spectroscopy detected PET as the major polymer of MPs constituting about 97.9 and 88.7% of the inlet and outlet samples, respectively.	(Maurizi et al., 2023b)
Catalonia, Spain	360 L (3 replicates of 120 L each) of river water (Raw water) + effluent	Optical+ stereoscopic microscope+ FTIR	Raw water = 4.23 MPs/L Effluent = 0.075 MPs/L	Fibers = 77% in Raw water, 27% in the effluent+ fragments = 13% in Raw water, 47% in the effluent + films = 10% in Raw water, 26% in the effluent	MPs were mostly of size ranging between 500 and 100 μm (43%). Among the 22 polymers detected, Polyester was the predominant in the effluent (up to 25%). While in the effluent samples, Mps were mostly composed of synthetic cellulose (up to 47%).	(Dronjak et al., 2022)
South-western part of Norway	12 m3 of drinking water from 4 sites	pyr-GCMS	6.1 to 93.1 μg/m3	–	The polymer composition of MPs was as follows: PE (21–82%) > PA (0–36%) > PET (0–35%).	(Gomiero et al., 2021)
North Jutland	Danish drinking water plant fed with groundwater (1 m3 for each triplicate)	μRaman spectroscopy	1.4 MP counts/L OR 4 pg/L.	PA, PP, PS and PET	On day 2, MP counts were significantly higher (up to 3 times) than raw water. MPs were mostly made up of PA polymers when estimated concerning counts. They were present up to 39% and 78% in 3/5 inlet and outlet samples, respectively. However, when inlet samples MPs were assessed in terms of mass, the polymer dominancy on days 1; 2, and 5; and 3 and 4 was as follows: PA > PA > Polyacrylics, respectively. In outlet samples, poly-acrylic was the major polymer on all days (up to 55–72%). MPs were mostly of the size ranging between 1 and 5 μm, constituting about an average of 83.3 and 92.7% in inlet and out samples, respectively. According to estimates, An annual consumption of MPs was 4.4 ng/year.	(Maurizi et al., 2023a)
California	Three spiked samples of simulated clean water and a laboratory blank	optical microscopy+ FTIR + Raman spectroscopy	Clean Water samples = 76% Blank sample = 91 particles	PE, PP, PS, PET and PVC particles were detected	92% of MPs were of sizes 20–212 μm, 212–500 μm and > 500 μm. MPs were detected in six colors: clear, white, green, blue, red, and orange. Their composition was consisted of PE, PS, PVC, and PET polymers.	(De Frond et al., 2022)
Valencia, Spain	5 L drinking water from 3 DWTPs	Rose Bengal dye staining + Nile Red and iDye Pink staining+ epifluorescence microscope+ μFT-IR+ Raman micro-spectroscopy	DWTP A = 83 MP/L DWTP B = 52 MP/L DWTP C = 61 MP/L	Fibers (84–94% for DWTP A, 85–92% for DWTP B and 85–89% for DWTP C) + Fragments (6–16% for DWTP A, 8–15% for DWTP B and 11–15% for DWTP C)	MPs were mostly of white, unstained microfibers. PS polymer showed dominance in MPs constituting about 62 and 35% in DWTP B and DWTP C, respectively.	(Alonso-Vázquez et al., 2023)
Canada	seven different brands of bottled water(still and carbonated water)	Nile Red staining+ ATR-FTIR+ Py-GC–MS	67% were confirmed to be polymers in the drinking water sample	PE, PP, PS ad PET were detected	The optimized Nile Red concentration enabled the detection of microplastics as small as 1 μm in size.	(Hernandez et al., 2023)
South of Sweden (Skåne)	200 and 1100 L drinking water of DWTP from 5 stations	μFTIR and Py-GCMS	174 MPs/m3	19% fibers+81% particles	Fiber shaped MPs were mostly constituted of PE (up to 87%). Mostlt MPs were of sizes <150 μm. One person estimated annual intake is <1MP. BJP samples exhibited the maximum MPs counts up to 809 MPs / m3. By μFTIR, Samples obtained from BJP and BOH have MPs mostly made up of PE while BJH and BOP were of PA. By using the Py-GCMS technique, it was found that PE was the major polymer of BJP, BJH, and BOP samples. While V and BOH were made up of PVC and PS, correspondingly.	(Kirstein et al., 2021)
India	20 different brands of plastic water bottles (500 mL capacity)in Triplicates (60 samples)	Nile Red staining+ FTIR	5–70 MPs/500 ml	80% Fragments+20% Fiber	MPs size range was 23.83–353.24 μm. In detected MPs, PS was the major polymer.	(Mohan et al., 2023)
Kathmandu, Nepal.	Deionized water samples (n = 9) + bottled and jar water samples (n = 20)	Smartphone microscopic detection system	Deionized water = 34 particles/L Bottled water = 0–91 particles/L Jar water = 0–130 particles/L	PE, PP, PET And PS polymers were detected	The smartphone microscope detected microplastic particles larger than 20 μm, with particle counts ranging from 0 to 91 particles/L in bottled water and 0–130 particles/L in jar water, with 97% of the particles confirmed as plastic.	(Karki et al., 2024)

MPs (Micro plastics); (ATR) automated total reflectance; (PC) poly carbonate; (LB) lower bound estimate; (UB) Upper bound estimate; (LDPE) Low density polyethylene; (EVE) Ethylene-vinyl acetate; (PES) polyethersulphone; (SEM) Scanning electron microscopy; (NR) Nile red; (IR spectroscopy) infrared spectroscopy; (PEVA) Polyethylene Vinyl acetate; (LDIR) Laser direct infrared; (PS (polystyrene); (μFTIR) micro- Fourier-transform infrared spectroscopy; (DWTPs) Distilled water treatment plants; (TW) Treated water; (HDPE) High density polyethylene; (PS) Polystyrene; (PA) Polyamide; (PET/ PETE) Polyethylene Terephthalate; (PP) Polypropylene; (PU) Polyurethane; (PVC) Polyvinyl chloride; (PE) Polyethylene; (FTIR) Fourier-transform infrared spectroscopy; FE-SEM (field emission scanning electron microscope); WTPs (water treatment plants); CTs (consumption taps); (WTP) Water treatment plants; (pyr-GCMS) chromatography-mass spectrometry sample's analysis; (ATR-FTIR) Attenuated total reflection-Fourier transform infrared spectroscopy.

4.9. Critical comparison of detection techniques

Although numerous analytical techniques have been employed for the detection of microplastics (MPs) in drinking water, no single method provides an ideal balance between sensitivity, polymer identification accuracy, analytical throughput, and operational cost. Spectroscopic techniques such as FTIR and μFTIR are among the most widely adopted because they enable reliable polymer identification without extensive sample destruction. However, their ability to detect very small particles is limited, generally to sizes above approximately 10–20 μm, and sample analysis can be time-consuming. In contrast, μRaman spectroscopy offers superior spatial resolution and can identify particles as small as 1 μm, making it particularly suitable for detecting smaller MPs and some nanoplastic-sized particles. Nevertheless, fluorescence interference, longer acquisition times, and higher instrumentation costs restrict its routine application.

SEM provides high-resolution information on particle morphology and surface characteristics but cannot independently identify polymer composition without complementary spectroscopic techniques. Pyrolysis-GC–MS enables accurate quantitative determination of polymer mass and chemical composition but destroys the sample during analysis and does not provide information on particle morphology or abundance. Recently developed smartphone-based microscopy offers a rapid and inexpensive screening approach, making it promising for preliminary monitoring in resource-limited settings, although its sensitivity and polymer identification capability remain inferior to laboratory-based analytical methods.

Overall, FTIR-based methods are currently the most practical for routine monitoring, whereas μRaman and Py-GC–MS are better suited for detailed laboratory investigations requiring high sensitivity and chemical specificity. Future research should prioritize standardized analytical protocols, improved detection of particles below 1 μm, automation of data processing, and harmonization of quality assurance procedures to improve inter-study comparability.

5. Mitigation of MPs in drinking water

5.1. Mitigation by coagulation, flocculation, and filtration processes

Adib et al. (2022) investigated the impacts of poly aluminum chloride and poly acrylamide as conventional coagulants in the removal of MPs from drinking water. The results implicated the less removal efficiency of both conventional coagulants as they removed only about 19% of MPs in the dosage of 200 ppm (for poly aluminum chloride) and 21 ppm (for polyacrylamide) at pH 9. Tang et al. (2023) described that the coagulation behavior with MPs is an important factor in removal of MPs from drinking water. According to the investigation, the concentration and size of MPs had a significant impact on the coagulation behavior, but the size of MPs is more important than the concentration. The results indicated that poly aluminum chloride and poly acrylamide as a coagulant removed about 70% of MPs (with size of ≥13 μm) from samples of drinking water under study. In another research, Li et al. (2021) removed PS-based MPs of size 100 μm having a low density of 1.04 to 1.06 g/cm³ from drinking water samples by applying coagulation-flocculation and filtration processes. These methods exhibited efficient removal of PS MPs up to 98.9% due to the flocculant breakdown and regeneration at pH 5, 3.4 mg aluminum per L (dosage of the coagulant), 7 min of flocculation and 30 min of sedimentation time.

When MPs removal was examined from river water and distilled water treatment plants samples in Catalonia, NE Spain. There was a significant difference of 0.9 Mps/L MPs after the treatment of water following the coagulation, sedimentation, flocculation and ultrafilteration methods. Thus, their removal was up to 93% in which polyester and PE were the most predominant. The sand filtration unit showed the highest removal of MPs up to the 78%. It was also concluded that the methods of reverse osmosis and ultrafiltration exhibited higher MPs removal efficiency as compared to the ozonation and carbon filtration units (Dalmau-Soler et al., 2021). In another study, Radityaningrum et al. (2023) studied the removal of MPs from water samples of two conventional drinking water treatment plants (CDWTP) having intake, pre-sedimentation, coagulation-flocculation, sedimentation, sand filter, and disinfection units in the region of East Java, Indonesia. They found that MPs were removed by 66% in CDWTP-1and 62% in CDWTP-2. Among the 6 units present in CDWTP, the coagulation-flocculation unit removed the maximum level of MPs of up to 56%. Besides that, large-sized MPs showed higher removal efficiency i.e., the removal of MPs with the size range of 1–350 μm exhibited removal of 33–53% and the MPs with 351–5000 μm size exhibited the removal of 53–76%. Film-shaped MPs showed the highest removal of 100% followed by the fragment-shaped MPs with removal of 86–100%.

Velasco et al. (2023) compared the removal efficiency of MPs from drinking water treatment plant (DWTP) in Geneva, Switzerland by activated carbon filtration and sand filtration methods. The concentration of MPs in raw water was 25.7 to 55.6 MPs/m³ while in treated water, it was only 0 to 4 MPs/m³. The activated carbon filtration method was proved to be more efficient as it removed 97% of the MPs as compared to the sand filtration method with removal of 70% MPs from treated water samples. Most of the MPs retained in the drinking water were PE and PET. Cherniak et al. (2022) investigated the removal of MPs during the coagulation with aluminum hydroxide, flocculation, anthracite-sand filtration and chlorination stages in a conventional drinking water treatment plant. The samples were also taken from pilot-scale biological filters comprised of granular activated carbon or anthracite sand media. In treatment plant samples, MPs removal was up to 52% mostly of polyester polymer and fiber shaped with size range of 10–45 μm. While the coagulation, flocculation, and sedimentation showed the maximum removal of 70% individually. However, in pilot filter samples, it was noticed that there was a non-significant removal of the MPs. Li et al. (2024) investigated the removal of MPs in 4 drinking water treatment plants (DWTP-A, DWTP-B, DWTP-C, and DWTP-D) having intake, sedimentation tank outlet, and final outlet units. The DWTP-C had only liquid chlorine disinfection tank. When the treated water samples from the 4 DWTPs (2.5 L from each) in the region of Zhengzhou, China was examined for microplastic removal. It was determined that 45.8% to 74.5% MPs were removed in all plants. Among them, DWTP-C showed the lowest removal of MPs as compared to the other treatment plants. The PET was the most prevalent microplastic that retained in the treated drinking water samples. In another investigation, Ma et al. (2019) observed that, when water samples were treated with coagulation and ultrafiltration methods in the presence of Fe- based salts (FeCl₃·6H₂O), the size of MPs (PE) and polyacrylamide dosage played an important role in the removal of MPs. The anionic polyacrylamide at a higher dose, exhibited MPs removal of up to 90.9%, due to maximum adsorption capacity and dense flocculants development as compared to the conventional coagulation that removed only up to 15% of MPs.

Wang et al. (2020) described that the removal of MPs from drinking water depends upon their shape, size, and other physical properties. They investigated the synergistic effect of coagulation with sedimentation and the single effect of granulated activated carbon filtration on the removal of MPs from drinking water. It was found that the processes of coagulation and sedimentation removed the MPs up to the extent of 40.5 to 54.5% mostly of fiber shaped. While the filtration with granular activated carbon removed MPs up to 56.8 to 60.9% with 1–5 μm size. Shao et al. (2020) studied the effect of sodium hypochlorite, potassium permanganate, and ozone as pre-oxidants on the removal of MPs from drinking water. Furthermore, the processes of coagulation, sedimentation, and filtration using poly aluminum chloride as coagulant, were also employed to the water samples to evaluate the effect of pre-oxidation on the removal of MPs. The use of 30 mg L⁻¹ of coagulant during coagulation and sedimentation with pre-oxidants potassium permanganate, sodium hypochlorite, and ozone showed the enhanced MPs removal efficiency due to the change in functional groups, specific surface area, and hydrophobicity of the MPs. In another research, Tang et al. (2024) devised an advanced method of coagulation in which modified starch was used in addition to the use of poly aluminum chloride and poly acrylamide as conventional coagulants for the removal of MPs from drinking water. The removal efficiency was further enhanced using biochar filtration. The results showed that the use of conventional coagulants with modified starch removed more than 80% of the MPs and the addition of biochar filtration process to it enhanced the removal efficiency of MPs up to 97% that was exceptional removal efficiency.

5.2. Mitigation by pulse clarifiers

Sarkar et al. (2021) studied the removal of MPs from a drinking water treatment plant located in Ganga River, India using pulse clarifier (a setup in which the water gained an upward pressure with the help of pulsator plates, and the clarified water is collected through gutter for passing into the sand filtration step). The step of pulse clarification removed MPs upto an extent of 63% while the step of sand filtration removed 85% of the MPs. The large quantity of MPs was of fiber and fragment shaped with PE and PET as their main chemical types. The sand filtration unit performed better as compared to the pulse clarification unit in the removal of MPs. In another study, Islam et al. (2023) examined the MPs removal efficiency of water-treatment plants which used pulsator clarifiers, filtration beds, chlorination, and plant alums [Al₂(SO₄)₃ (14–18) H₂O] as water purification methods in Saidabad Water Treatment Plant phase-1 (SWTP-1) and 2 (SWTP-2), and Padma Water Treatment Plant (PWTP) in the region of Bangladesh. These plants removed 98.8, 98.5, and 99.2% of MPs respectively of size 20 μm to <5000 by treating 30 L of water in each process. Most of the MPs were of fragment and fiber shapes having an abundance (up to 48%) of PE.

5.3. Mitigation by boiling

Boiling caused MPs to aggregate or clump together, which make them easier to filter out if the water is filtered afterward. As the water is heated, MPs experience thermal expansion. Depending on their polymer composition, MPs may soften or become more pliable at elevated temperatures. Many MPs are hydrophobic in nature. In a hot, turbulent environment like boiling water, these hydrophobic particles may coalesce, seeking to minimize their exposure to water, thus promoting clumping. Boiling water generates strong convection currents that stir the water, bringing microplastic particles into contact with each other more frequently. This increases the likelihood of particles colliding and sticking together. In a study, the impact of boiling as a conventional technique to mitigate the levels of micro and nanoplastics in drinking water was investigated. It was observed that PE and PS got bind with CaCO₃ during the process of boiling and settled down. The results implicated that the boiling of the hardwater which had more than 120 mg L⁻¹ of CaCO₃ in it removed 80% of the above-mentioned micro and nanoplastics having size of 0.1–150 μm (Yu et al., 2024).

5.4. Mitigation by magnetic oxide composites

Magnetic oxide composites are materials that combine magnetic particles, typically iron oxides like magnetite (Fe₃O₄) or maghemite (γ-Fe₂O₃), with other substances, often polymers or other inorganic materials. These composites have magnetic properties that allow them to be manipulated using external magnetic fields. As MPs attach to the magnetic oxide composites, they may form larger aggregates. These aggregates are easier to manipulate and remove from the water. Once the MPs have adhered to the magnetic oxide composites, an external magnetic field is applied to the water. The magnetic oxide particles, along with the attached MPs, are attracted to the magnetic field and can be pulled out of the water. In an investigation, C@Fe3O4 composites were prepared by employing one-pot microwave synthesis method which acted as a magnet to adsorb MPs and organic pollutants from drinking water. The results indicated that the MPs got adhered to the composite and further attracted toward an external magnet, so it proved to be a new and efficient method as it removed the maximum levels of MPs from drinking water (Elmaci, 2020). The mitigation of MPs in drinking water is also described in Table 2.

Table 2.

Mitigation of microplastics in drinking water.

Samples under study	Technique/method employed	Treatment conditions	Removal efficiency	Other impacts observed	Overall findings	References
Ultra-pure water	Coagulation	60 ± 2 NTU, pH of 7.0 ± 0.2, 40.00 mg L−1 PAC, PAM 14.50 mg L−1, speed 198 S−1 and 40 S−1 for 1 and 15 mins respectively.	Removal efficiency of MPs with size ≥13 μ m could reach >70% by PAC and PAM	A pH range of 7 to 9 was identified as the optimal condition for the coagulation of MPs.	The size and concentration of MPs had a more significant influence on their removal, with size being the primary factor, while the type of MPs had the least effect on the coagulation behavior.	(Tang et al., 2023)
Tap water	Boiling	40 mL deionized water, boiled for 5 min, at 25–100 °C, 180 mg L−1 of CaCO3	Boiling hard water (>120 mg L−1 of CaCO3) can remove at least 80% of PS, PE, and PP NMPs size between 0.1 and 150 μm	Increased temperatures facilitate the nucleation of CaCO3 on NMPs, leading to their encapsulation and aggregation within CaCO3 deposits.	This straightforward boiling-water method can effectively decontaminate NMPs from household tap water and holds potential for safely reducing human exposure to NMPs through water consumption.	(Yu et al., 2024)
Drinking water from water treatment plants.	Pulsator clarifier in SWTP-1 and SWTP-2 coagulation/flocculation, and sedimentation in PWTP.	20μmpore-sized stainless-steel sieve, 30% H2O2 solution, Analytical reagent grade ZnCl2, 97% min, Cellulose nitrate membrane filters of 0.45 μm	The removal efficiencies of MPs with size <300 μm were found to be 98.8%, 98.5%, and 99.2% for SWTP-1, SWTP-2, and PWTP, respectively	The remaining MPs were found to be contaminated with heavy metals such as Pb, Cd, Cr, As, Cu, and Zn.	The effectiveness of microplastic removal in the three examined DWTPs was remarkable, at least within the size range of 20 μm–0.05 μm and showed no significant differences (p > 0.05).	(Islam et al., 2023)
Raw water from river (CDWTPs I and II).	Conventional drinking water treatment plant (CDWTP) (Intake, pre-sedimentation, coagulation-flocculation, sedimentation, sand filter, and disinfection units).	10 mL of 30% Merck H2O2 and 10 mL of Fe (II) 0.05 M, 75 °C, 0.2 μm and 47 mm diameter membrane.	Total MP removal efficiencies in CDWTPs I and II were 66 and 62%, respectively.	The coagulation-flocculation unit achieved the highest removal efficiency for MPs, at 56%. In the case of the CDWTPs, the removal efficiencies for fibers, fragments, and films were 61–65%, 86–100%, and 100%, respectively.	MPs in the size range of 1–350 μm had lower removal efficiencies (33–53%) compared to those in the 351–<5000 μm range, which achieved higher removal rates (53–76%).	(Radityaningrum et al., 2023)
Drinking water	DWTP (sand filtration, GAC filtration, reverse osmosis)	8 cm high × 10 cm diameter, particles with size range from 20 μm to 5 mm, sand filter (50 L) and GAC filter (50 L), reverse osmosis (100L) and treated water (100 L)	Overall removal efficiency of 93 ± 5%.	Sand filtration was identified as the critical stage for microplastic removal, achieving an efficiency of 78 ± 9%.	Ultrafiltration and reverse osmosis (advanced treatment) are more effective for removing microplastics compared to the ozonation and carbon filtration stage (upgraded conventional treatment).	(Dalmau-Soler et al., 2021)
Drinking water	Coagulation, filtration systems (sand and activated carbon)	Four stainless steel sieves (ISO 3310-1) of 200 mm diameter with 500, 250, 125, and 63 μm mesh sizes	Removal efficiency of MPs (97%) and synthetic fibers (96%) was observed in drinking water with coagulation treatment	The treated water, following coagulation, sand filtration, and ACF, was found to contain a negligible amount of microplastics (2.6 MPs/m3) and synthetic fibers (0.3 SF/m3), with removal efficiencies exceeding 96%.	MPs smaller than 250 μm were found to be predominant in the drinking water treatment plant.	(Negrete Velasco et al., 2022)
Drinking water	PACl was applied as a Conventional coagulant	pH 9, 200 ppm of PACl, PPMPs size of d < 0.25 mm, and 21 ppm of PAM	Maximum removal rate of 18.75 ± 1.48%	The size of PP microplastics and the dosage of PACl exhibited an inverse relationship with the removal rate; as the size of PP microplastics and the PACl dosage decreased, the removal rate increased.	Conventional DWTPs that use ferric chloride or PACl as coagulants are unable to remove PPMPs.	(Adib et al., 2022)
Drinking water	Coagulation with aluminum hydroxide, flocculation, anthracite-sand filtration, and chlorination	Sieves with 500 μm, 300 μm, 125 μm, and 45 μm openings followed by filtration through 10 μm polycarbonate filters	Coagulation, flocculation, and sedimentation accounted for the highest removal (70%) of any individual unit process	This study demonstrates that the removal efficiency of conventional treatment methods may be constrained when addressing microfibers.	The majority of the particles (>80%) were identified as fibers measuring 10–45 μm. The microplastics were mainly composed of polyester, whereas the non-plastic anthropogenic particles consisted primarily of cellulose.	(Cherniak et al., 2022)
Drinking water	Coagulation, followed by the application of biochar filtration	PE powder with size of <6.5 μm, 60 ± 2 NTU, 5 g starch, 3 g NaOH,	The removal efficiency of MPs by modified starch / PAC + PAM was >80%.	MPs present in the coagulation effluent could be effectively removed by biochar, achieving a removal efficiency exceeding 90%. Additionally, the coagulation-filtration process demonstrated remarkable efficacy in removing microplastics, with removal efficiencies reaching as high as 97%.	The effectiveness of both the modified starch coagulant and the biochar filtration process in improving the removal efficiency of MPs was clearly demonstrated.	(Tang et al., 2024)
Raw water	Pulse clarification and sand filtration	Coagulant (H2SO4 Al2(SO4)3 24H2O), dose: 3000 L/h, upward flow (550 m3/h), and bed with size, 84 m2; depth, 0.95 m; particle size, 1.1–1.5 mm	Cumulative MP removal with pulse clarification and sand filtration was found to be 63% and 85%, respectively	The study also revealed a higher abundance of MPs on the sand filter bed, attributed to the screening effect. The most commonly occurring microplastics were fibers and films/fragments, with PET and PE identified as the predominant chemical types.	The tested DWTP equipped with a pulse clarification system exhibited a MPs removal efficiency comparable to that of previously reported advanced DWTPs.	(Sarkar et al., 2021)
Drinking water	Coagulation, sedimentation, and filtration	(50 mesh, 250–300 mm, 1 mM hydrochloric acid solution, vacuum-drying at 60 ○C for 24 h, 36.2% humic acid.	Due to pre-oxidation, there is no influence on the removal of PE MPs by conventional drinking water treatment processes	Pre-oxidation modified the adsorption capacity of PE microplastics for trace organic matters, as well as their surface contact angle (hydrophobicity), micromorphology, and interfacial functional groups.	Current findings indicate that pre-oxidation may elevate the risk of pathogenic microorganisms by enhancing the oxidization-induced ability of MPs to shelter these microorganisms.	(Shao et al., 2020)
Drinking water	Coagulation-flocculation and sedimentation	3.4 mg Al/L of coagulant, pH 5, flocculation time of 7 min and sedimentation time of 30 min	Percentage removals were 98.9 ± 0.94%	Floc breakage and regrowth following the addition of aluminum have been shown to enhance the removal of PS beads.	Coagulation-flocculation can be crucial in the removal of MPs during drinking water treatment.	(C. Li et al., 2021)
Drinking water	Coagulation combined with sedimentation and GAC filter, coagulation/flocculation, sedimentation and sand filtration.	30% hydrogen peroxide (H2O2), 5 μm, 0.22 μm 30 ○C for 30 min	Ozonation integrated with GAC filtration increased the removal efficiency by about 17.2–22.2%	The conventional treatment process, which includes coagulation/flocculation, sedimentation, and sand filtration, achieved a removal efficiency of approximately 58.9–70.5%. Furthermore, no MPs greater than 10 μm were detected in the effluent from sand filtration.	This study enhances our understanding of the removal behavior of MPs in DWTPs and is significant for managing MP pollution in these facilities.	(Wang et al., 2020)
Raw water	DWTPs in Zhengzhou city. (coagulation/flocculation and sedimentation)	2.5 L of water, 10 μm, 50 mL of 30% H2O2, 50 °C	The removal rate of MPs ranged from 45.8% to 74.5%	Fibers and fragments measuring between 10 and 100 μm were identified as the primary components of MPs in all water and sludge samples. However, in the treated drinking water sample from DWTP-D, the dominant size range shifted to between 100 and 500 μm.	A total of seven different colors of MPs were identified, with white and transparent being the most common.	(Y. Li et al., 2024)
Drinking water	C@Fe3O4 composites	PS beads (3 μm), ammonium hydroxide (30–32%), resistivity ˂ 18 MΩ × cm, 30 mins.	The introduced microwave process led to the production of homogeneous particle size distribution Fe3O4 (∼ 90 nm) and high surface area carbon support (250.1 m2/g), using low-cost starting materials.	MPs adhered to the composite surface were effectively removed from the water using an external magnet.	This study presents a novel method for the rapid, efficient, and cost-effective removal of microplastic pollutants from drinking water.	(Elmaci, 2020)
Drinking water	DWTP Geneva Switzerland (coagulation, filtration and ozonation)	1.4 m3/s,	70% of MPs was removed after sand filtration and coagulation, ozonation and GAC has 98% removal efficiency,	The concentration of identified synthetic fibers was low, with an average value of 2 synthetic fibers per cubic meter and remained consistent throughout all stages of water treatment.	The concentrations of MPs in raw water vary between 25.7 and 55.6 MPs per cubic meter, while in treated water, they range from 0 to 4 MPs per cubic meter.	(Negrete Velasco et al., 2023)
Drinking water	Coagulation and Ultra filtration processes	1 mol/L HCl, Humic acid, 2 g/L, 4 °C, 0.1 mol/L NaHCO3, 0.1 mol/L NaOH/HCl, 1 min at 300 r/min (278 S − 1), and then decreased to 100 r/min (18.9 S − 1) for 14 min, and 30 min for sedimentation	Higher removal efficiency was induced for smaller PE particles, low PE removal efficiency (below 15%) was observed using the traditional coagulation process, and was little influenced by water characteristics	The removal efficiency of PE increased with a higher dosage of ferric chloride hexahydrate (FeCl₃·6H₂O) at 2 mmol/L, and this efficiency further improved with an increase in solution pH.	The removal efficiency of PAM for microplastics was minimally affected by water conditions such as ionic strength, NOM, and turbidity. In comparison to cationic PAM, anionic PAM exhibited significantly higher removal efficiency due to its opposing charge relative to the Fe-based flocs under neutral conditions.	(Ma et al., 2019)

NTU, nephelometric turbidity unit; PAC, poly aluminum chloride; PAM, Polyacrylamide; MPs, micro plastics; PS, polystyrene; PE, polyethylene; PP, polypropylene; CaCO_3, calcium carbonate; SWTP, saidabad water treatment plant; PWTP, padma water treatment plant; H₂O_2, hydrogen peroxide; ZnCl₂, zinc chloride; Pb, lead; Cd, cadmium; Cr, chromium; As, arsenic; Cu, copper; Zn, zinc; DWTPs, drinking water treatment plants; CDWTP, conventional drinking water treatment plant; DWTP, drinking water treatment plant; PET, polyethylene terephthalate; GAC, granular activated carbon; ACF, activated carbon filtration; PACl, polyaluminium chloride; PPMPs, polypropylene microplastics; NOM, natural organic matters.

5.5. Critical evaluation of mitigation strategies and practical implementation

Current mitigation technologies differ substantially in terms of removal efficiency, operational complexity, scalability, and economic feasibility. Conventional treatment processes, including coagulation–flocculation, sedimentation, and rapid sand filtration, can effectively remove a considerable proportion of larger microplastic particles and are readily applicable because they are already integrated into municipal drinking water treatment plants. However, their efficiency decreases considerably for particles smaller than 10–20 μm and nanoplastics.

Advanced membrane technologies, including ultrafiltration, nanofiltration, and reverse osmosis, generally provide the highest removal efficiencies but require substantial capital investment, higher energy consumption, membrane maintenance, and management of concentrated waste streams. Emerging adsorbents, including magnetic oxide-based composites and functional nanomaterials, demonstrate promising laboratory-scale performance and selective removal capabilities; however, their long-term stability, regeneration potential, environmental safety, and large-scale economic feasibility remain insufficiently investigated.

Although boiling has been reported to reduce microplastic exposure in household drinking water, its effectiveness depends on water chemistry and is not suitable as a universal solution. Consequently, no single mitigation technology can eliminate MPs under all operating conditions. An integrated multi-barrier treatment strategy combining optimized conventional treatment with advanced membrane separation or adsorption technologies is likely to provide the most effective approach for minimizing microplastic contamination. Future research should emphasize pilot-scale validation, life-cycle assessment, cost-effectiveness analysis, and the development of standardized performance evaluation criteria to facilitate practical implementation in drinking water treatment systems.

5.6. Practical considerations for microplastic removal in drinking water treatment systems

Although numerous laboratory studies have demonstrated promising microplastic removal efficiencies, translating these findings into full-scale drinking water treatment plants remains challenging. Conventional treatment processes, including coagulation–flocculation, sedimentation, rapid sand filtration, and granular activated carbon filtration, are already capable of removing a substantial proportion of larger microplastic particles and therefore represent the most immediately applicable strategies for municipal water treatment. However, their performance is influenced by microplastic size, shape, density, polymer composition, co-existing natural organic matter, and variations in raw water quality.

Several advanced technologies, including membrane filtration, magnetic oxide-based adsorbents, and other engineered nanomaterials, have shown excellent removal efficiencies under laboratory conditions. Nevertheless, their practical implementation is constrained by high operational and maintenance costs, membrane fouling, regeneration requirements, energy consumption, and uncertainties regarding long-term environmental safety. Furthermore, the effectiveness of these technologies under continuous operation and varying hydraulic conditions remains insufficiently investigated.

Another important consideration is that drinking water treatment alone cannot completely prevent microplastic contamination. Several field studies have reported increased microplastic concentrations within distribution networks due to the aging of plastic pipes, mechanical abrasion, maintenance activities, and household plumbing materials. Therefore, improving drinking water quality requires a comprehensive approach that combines optimized treatment processes, careful selection and maintenance of distribution infrastructure, standardized monitoring protocols, and continuous surveillance throughout the entire drinking water supply chain. Future research should prioritize pilot-scale and full-scale investigations to validate laboratory findings and support the implementation of technically feasible and economically sustainable microplastic mitigation strategies.

6. Challenges, conclusion, and future recommendations

6.1. Challenges associated with detection

MPs in drinking water can be detected using a range of analytical techniques, including FTIR, SEM, Pyr-GC–MS, chemical imaging systems, and mobile phone-based screening methods. Each technique exhibits distinct performance characteristics, limitations, and operational challenges. FTIR spectroscopy is widely used due to its reliability in polymer identification; however, its sensitivity is limited for smaller particles (typically <20 μm), and sample preparation can be time-intensive. Raman spectroscopy offers higher spatial resolution and improved detection of smaller MPs compared to FTIR, though it is often affected by fluorescence interference and requires careful calibration. The integration of Raman spectroscopy with SEM enhances both morphological and chemical characterization, but this combined approach is costly and less scalable for routine monitoring.

Pyr-GC–MS provides highly accurate qualitative and quantitative analysis by thermochemically decomposing polymers into characteristic fragments. Despite its high sensitivity and reproducibility, the technique is destructive, labor-intensive, and requires sophisticated instrumentation, limiting its applicability for high-throughput or field-based analysis. Chemical imaging and fluorescence-based staining methods enable improved visualization and semi-quantification of MPs, particularly for smaller particles, yet challenges remain regarding dye selectivity, potential overestimation, and interference from organic matter. Mobile phone-based detection systems represent a rapid and low-cost screening approach with potential for field deployment; however, their current limitations include low quantification accuracy, dependence on imaging resolution, and the need for advanced image-processing algorithms.

From a practical standpoint, most of these detection techniques are predominantly laboratory-based and require extensive sample preparation, specialized expertise, and controlled conditions. Their application in real drinking water treatment facilities is therefore constrained by factors such as time, cost, and the need for continuous monitoring. Emerging efforts are focused on developing portable, automated, and real-time detection systems that can be integrated into existing water treatment infrastructure.

6.2. Challenges associated with mitigation

Regarding mitigation strategies, conventional treatment processes such as coagulation, flocculation, and filtration have demonstrated considerable efficiency in MP removal, particularly for larger particles (>10–20 μm). The effectiveness of these processes depends on operational parameters such as coagulant type, dosage, mixing conditions, and filter media characteristics. Chemically active coagulants (e.g., aluminum- and iron-based salts) enhance aggregation and subsequent removal of MPs; however, their large-scale application may generate secondary environmental concerns, including sludge production and chemical residues.

Boiling has been identified as a simple and low-cost household-level intervention that can reduce MP concentrations, especially when followed by filtration; nevertheless, it is not suitable for large-scale water treatment and may incur additional energy costs. Advanced materials, such as magnetic oxide composites, exhibit high removal efficiency due to their strong adsorption capacity and ease of separation under magnetic fields. Despite their effectiveness in laboratory settings, challenges related to scalability, cost, regeneration, and potential environmental risks associated with nanoparticle release limit their practical implementation in full-scale treatment plants.

The majority of mitigation strategies have been validated under controlled laboratory conditions, and their performance under real drinking water treatment scenarios remains insufficiently explored. In operational treatment plants, factors such as variable water quality, presence of natural organic matter, hydraulic conditions, and infrastructure limitations can significantly influence MP removal efficiency. Therefore, future research should prioritize pilot-scale and full-scale studies to evaluate the long-term efficiency, economic feasibility, scalability, and potential secondary environmental impacts of these technologies. Such efforts are essential to bridge the gap between laboratory findings and real-world applications, ensuring effective and sustainable control of microplastic contamination in drinking water systems.

6.3. Future recommendations

Future research on the detection of MPs in drinking water should focus on developing standardized, sensitive, and field-deployable analytical methods to overcome the limitations of current laboratory-based techniques. Harmonization of sampling protocols, sample preparation, and analytical procedures is essential to ensure data comparability and reliability across studies. Advancements in hyphenated techniques (e.g., coupling spectroscopic methods with automated imaging systems) and the integration of machine learning algorithms can enhance detection accuracy, reduce human bias, and enable high-throughput analysis. Particular emphasis should be placed on improving the detection of smaller MPs and nanoplastics, which remain inadequately characterized due to current technological constraints. The development of portable and cost-effective sensing platforms, including enhanced mobile phone-based systems with high-resolution imaging and real-time data processing capabilities, holds significant promise for on-site monitoring and rapid screening in drinking water systems.

Future mitigation strategies should prioritize the scalability, efficiency, and environmental sustainability of technologies for MP removal in drinking water. While conventional processes such as coagulation, flocculation, and filtration remain effective, further optimization under real-world treatment conditions is necessary to enhance their performance across varying water qualities. Emerging materials, such as magnetic oxide composites and other advanced adsorbents, require comprehensive evaluation in terms of large-scale applicability, cost-effectiveness, regeneration potential, and risks of secondary contamination. There is a pressing need for pilot-scale and full-scale studies within operational water treatment facilities to validate laboratory findings and assess long-term performance. Future research should also incorporate life cycle assessment and techno-economic analysis to evaluate the overall sustainability of mitigation approaches, while addressing potential environmental trade-offs such as sludge generation, chemical residues, and nanoparticle release.

CRediT authorship contribution statement

Sadia Younis: Writing – review & editing, Writing – original draft, Methodology, Investigation, Formal analysis, Conceptualization. Syed Ali Hassan: Writing – review & editing, Writing – original draft, Supervision, Methodology, Investigation, Conceptualization. Tehmina Naseem: Writing – original draft, Investigation, Formal analysis. Khushi Ali: Writing – original draft, Investigation, Formal analysis. Muhammad Irfan: Visualization, Software, Resources. Mueen Abbas: Writing – review & editing, Investigation, Formal analysis, Data curation. Muhammad Asif: Writing – review & editing, Data curation. Nabila Aslam: Writing – review & editing. Syed Junaid Zafar: Writing – review & editing. Maryam Abbasi Tarighat: Writing – review & editing, Supervision, Software. Gholamreza Abdi: Writing – review & editing, Supervision, Project administration, Investigation, Formal analysis, Data curation.

Consent to publish

All authors have reviewed the manuscript and consent to its publication.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors. Ethical approval was not required for this review article.

Funding

This work received no funding from internal or external sources.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability

Data will be made available on request.