Table 1.
Comparison of household water purification interventions
| Method | Availability and practicality | Cost (a) | Microbial efficacy (b) | Limitations |
|---|---|---|---|---|
| Boiling | Varies (c) | Depend on fuel | High | Time consuming / High cost / Recontamination / Loss of mineral |
| Exposure to Sunlight | High | Low | Moderate | Weather conditions / water should not be turbid |
| UV Irradiation (lamps) | Varies (d) | Moderate-high (d) | High | High cost/ regular maintenance/ piped water supply / Electricity is required |
| Plain sedimentation | High | Low | Low | Time consuming/Low efficacy |
| Filtration (ceramic, membrane filters) | Varies (e) | Varies | Varies | Cost/Regular cleaning of filters/Efficacy varies on size of pores of filters |
| Coagulation and Precipitation (e.g. Alum) | Moderate | Varies | Varies | Time consuming/Efficacy varies/Excess coagulant gives metallic taste |
| Adsorption (charcoal, carbon, clay, etc.) | High to moderate | Varies | Varies with adsorbent | Regular cleaning/ replacement of adsorption media at regular interval |
| Ion exchange (Resins with iodine e.g. Zero B) | Low to Moderate | Usually High | Low or moderate | Cost/Regular maintenance or cleaning |
| Chlorination | High to Moderate | Moderate | High | Less effective in turbid water |
| Filtration/ activated carbon adsorption/UV rays disinfection (Aquaguard by Eureka Fobres and Zero B water purifiers) | Varies | High | High | High cost/Electricity /periodic expenditure and maintenance |
(a)
Categories for annual household cost estimates in Rupees are less than Rupees 500 for low, >Rupees 500-5000 for moderate and >Rupees 5000 for high.
(b)
Categories for microbial efficacy are based on estimated order-of-magnitude or log10 reductions of waterborne microbes by the treatment technology. The categories are <1 log 10 (<90%) is low, 1 to 2 log 10 (90-99%) is moderate and >2 log 10 (>99% is high).
(c)
Depends on heating method as well as cost of fuels, which range from low to high.
(d)
Depends on type of lamps, cost of electricity, as well as maintenance
(e)
Practicality, availability, cost and microbial efficacy depend on the filter medium e.g. Membrane, ceramic, fabric,