Long-Term Behavior of Simulated Partial Lead Service Line Replacements

Abstract

In this 48-month pilot study, long-term impacts of copper:lead galvanic connections on lead release to water were assessed without confounding differences in pipe exposure prehistory or disturbances arising from cutting lead pipe. Lead release was tracked from three lead service line configurations, including (1) 100% lead, (2) traditional partial replacement with 50% copper upstream of 50% lead, and (3) 50% lead upstream of 50% copper as a function of flow rate, connection types, and sampling methodologies. Elevated lead from galvanic corrosion worsened with time, with 140% more lead release from configurations representing traditional partial replacement configurations at 14 months compared to earlier data in the first 8 months. Even when sampled consistently at moderate flow rate (8 LPM) and collecting all water passing through service lines, conditions representing traditional partial service line configurations were significantly worse (≈40%) when compared to 100% lead pipe. If sampled at a high flow rate (32 LPM) and collecting 2 L samples from service lines, 100% of samples collected from traditional partial replacement configurations exceeded thresholds posing an acute health risk versus a 0% risk for samples from 100% lead pipe. Temporary removal of lead accumulations near Pb:Cu junctions and lead deposits from other downstream plastic pipes reduced risk of partial replacements relative to that observed for 100% lead. When typical brass compression couplings were used to connect prepassivated lead pipes, lead release spiked up to 10 times higher, confirming prior concerns raised at bench and field scale regarding adverse impacts of crevices and service line disturbances on lead release. To quantify semirandom particulate lead release from service lines in future research, whole-house filters have many advantages compared to other approaches.

The pervasive threat of lead (Pb) in drinking water: Unmasking and pursuing scientific factors that govern lead release

“…Pb-based solder is used to connect piping, and Pb is present in trace amounts in Cu-rich alloys and disproportionately, preferentially leaches out into drinking water in greater quantities than predicted by the content of Pb in the alloy ( 22 ). There is a significant amount of Pb trapped in the oxides on iron pipes as well ( 3 , 31 – 33 ). Unless all galvanized steel pipes used in the same system with Pb pipe are also replaced, these oxides remain as potential sources of Pb.…”

“…Partial replacement of a Pb pipe with copper pipe can establish a galvanic corrosion cell when Pb and copper are in close proximity ( 33 – 36 ). In this galvanic cell, Pb corrosion is accelerated to higher rates than in the absence of copper (or steel as well) ( 33 – 36 ). Moreover, while total replacement of Pb service lines is a wonderful goal, finding all sources of Pb can be difficult.…”

Effectiveness of Prevailing Flush Guidelines to Prevent Exposure to Lead in Tap Water

“…While not a planned part of the study, conditions arose which allowed us to evaluate the impact of a one-time 15-min utility flush on WLLs after lead service lines replacements at five residential sites. Lead service line replacements and construction are known to increase lead in water due to construction disturbances and galvanic corrosion for periods of weeks to years [ 19 , 30 , 38 ]. While over ten years have passed since Hurricane Katrina, the rebuilding process is still ongoing, and the city of New Orleans is still in the process of conducting 16,000 PLSLRs [ 48 ].…”

“…The Washington DC, USA Lead Crisis (2001–2004) first demonstrated that the standard water Pb avoidance flushing guidance was inadequate during AL exceedances, and that flushing for only 15–30 s would directly expose consumers to hazards of water that had been held within the lead service lines [ 15 , 18 ]. A decade of follow up research has since confirmed that flushing protocols which reduce exposure in a given home, are highly dependent on variables that are difficult or impossible to control, including, but not limited to the length, configuration, material, condition and disturbance of service lines or plumbing, water use patterns, spatial changes in chemical and microbiological water quality within a given distribution system; and type of Pb released (particulates vs. dissolved) [ 2 , 3 , 11 , 14 , 15 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. In light of the evidence challenging the efficacy of flushing under different conditions, the EPA identified a need to further evaluate flushing [ 38 ] and revised the Lead and Copper Rule and Consumer Confidence Report Rule to allow utilities to modify the required flush time recommendations if they determine longer flush times are needed [ 17 , 39 , 40 ].…”

Phenolation of cyclodextrin polymers controls their lead and organic micropollutant adsorption

“…The contamination of groundwater and surface water by heavy metals and organic micropollutants (MPs) is a world-wide problem 1–4. There is no safe level for lead in drinking water 5.…”