TABLE 2.
Overview of coupon bench top studies reviewed.
| Studya | Intent | Water chemistry | Plumbing material | Stagnation regime | Sampling | Durationb | Replicates |
|---|---|---|---|---|---|---|---|
| Lytle et al. (1992) | Compare the % of lead (and other metals) in brass alloys to metal leaching | Water from tap w/pH adjustments (30 mL per Teflon sample cell) | New metal sheet coupons of brass, lead,
copper, zinc, and 60:40 Pb/Sn solder (1″ x 2″ × 1/8″) |
1 day | 1× per day for several weeks then 2× per week | 150 days (21.4 weeks) | Not specified |
| Lin et al. (1997) | Compare effects of free and combined chlorine on lead leaching | Finished water from treatment plant w/adjustments (disinfectant, pH, inhibitor) (1 L per plastic beaker) | New metal sheet coupons of lead, copper (coated w/lead solder), and brass (0.5″ × 4″ × 1/32″) | Mixed once per day for 30 min. No mention of water change except for inhibitor experiments |
1× per week | 5 weeks | Not specified except for brass coupons (duplicates) |
| Nguyen et al. (2010) | Examine the impacts of chloride-to-sulfate mass ratio (CSMR) on lead leaching | Finished water from a water utility (40 mL per jar) | New brass rod coupons (0.25″ dia, 0.38″ h) | 2–3 days | 3× per week (weekly composites of all 3 water changes) | 11 weeks | Triplicates |
| Examine the impact of treatment changes on lead leaching | Finished water from 10 utilities w/adjustments (inhibitor dosing, pH, treatment processes that affect CSMR) (25–100 mL per jar) | New brass (1/4″ dia), and copper (1/2″ dia) pipe coupons (1″); 50:50 Pb/Sn solder (0.125″ dia, 0.854″ h) | 3–4 days | 2× per week (weekly composites of both water changes) | 18–35 weeks | Duplicates/ triplicates |
|
| Bradley (2018) | Examine the effects of inhibitors on high CSMR water from two utilities | Raw water from two utilities treated in lab to simulate plant treatment w/adjustments (inhibitor, chloride) (50–100 mL) | Copper pipe coupons (3/8″ dia) with 50:50 lead: tin solder (1/2″ h) | Jars mixed at 25 rpm; water change every 2– 3 days | 3× per week (weekly composites of all 3 water changes | 14–16 weeks | 5 replicates |
| Roth et al. (2018) | Examine the impact of blended surface and ground water on lead leaching | Synthetic water representative of 2 water utilities (500 mL per jar) | New lead coupons (3″ × 1/2″ × 1/16″) |
3–4 days | 2× per week | Phase 1: 7 weeks Phase 2: 5 weeks |
Phase 1: duplicates Phase 2: duplicates split into two conditions (one replicate per condition) |
| Tang et al. (2018) | Examine the effect of water conditions on metal leaching | Finished water (surface and ground water sources) (125 mL per jar) | Harvested galvanized iron pipe coupons (0.5–1″ dia; 0.79″ h) | Weeks 0–5.5: 2–3
days Weeks 5.5–9: 7 days Weeks 9–13.5: 2–3 days |
Weeks 0–5.5: 3× per
week Weeks 5.5–9: 1× per week Weeks 9–13.5: 3× per week (weekly composites water changes) |
Pre-testing: 4 weeks Study: 13.5 weeks |
Pre-testing period used to determine “good” and “bad” coupons. Triplicate “good” and “bad” coupons for each water condition |
| Cornwell and Wagner (2019) | Determine effective corrosion control treatment (CCT) on lead leaching | Finished water from utilities w/adjustments (pH, inhibitor) (250–500 mL per jar) | New metal sheet coupons of lead, copper, mild steel, and brass(1/2″ × 3″) | 3–4 days | 1–2 × per week | ~ 1 year | Duplicates |
| CDPHE (2019), Arnold et al. (2021) | Compare effects of CCT on lead
leaching Examine the effect of changing coagulants at a surface water treatment plant (WTP) |
Finished water from 2 utilities w/adjustments
(pH, inhibitor) Finished water and raw water (with simulated treatment in lab) provided by WTP (125 mL per jar) |
New leaded brass and copper pipe coupons (1/2″ dia, 1″ h), copper pipe (1/2″ dia, 1″ h), with 50:50 lead/tin solder (0.125″ dia, 1″ h) | 2–3 days | 3× per week (weekly composites of all 3 water changes) | 6 weeks | Triplicates for leaded brass and copper pipe coupon tests 5 tests for copper pipes with 50:50 lead/tin solder |
| Masters et al. (2022) | Examine the effect of pH and orthophosphate on lead leaching | Water from treatment plant, after filtration but before secondary disinfection, with adjustments (pH, inhibitor) (240 mL per jar) | New lead coupons (2″ × 2″ × 0.063″) w/ 0.188″ dia hole. | Jars mixed at 50 rpm; water change 2–3 days | 3× per week (weekly composites of all 3 water changes) | Conditioning: 6 weeks Study: 7 weeks |
Triplicates |
Note: This list is not exhaustive and follow-up studies using similar set-ups were excluded for brevity.
Clarifications: Finished drinking water: water directly from the drinking water treatment plant that has not come in contact with any plumbing within the distribution system; Synthetic water: water made in the lab by adding chemicals to deionized water to simulate finished drinking water; Tap water: water from the tap in the lab (this differs from finished water which comes directly from the treatment plant and does not come in contact with any plumbing material within the distribution system).
Conversions: 1″ = 25.4 mm
Abbreviations: Dia, pipe diameter (inner/outer diameter not specified in paper); h, height of pipe coupon; w/, with.
a
This table includes studies (historical to 2022) with enough level of detail to fill each column.
b
Duration accounts for pre-testing and conditioning (if mentioned) as well as actual testing phases.