Effect of Flow Rate and Lead/Copper Pipe Sequence on Lead Release from Service Lines

By Cartier, Clément; Jr., Roger B. Arnold; Triantafyllidou, Simoni; Prévost, Michà¨le & Edwards, Marc
Published in Water Research NULL 2012

Abstract

A pilot experiment examined lead leaching from four representative configurations of service lines including: (1) lead (Pb), (2) copper (Cu), (3) 50% Pb upstream of 50% Cu, and (4) 50% Pb-downstream of 50% Cu using a range of flow rates. The cumulative mass of lead release indicated that a typical partial replacement configuration (50% lead downstream of copper) did not provide a net reduction in lead when compared to lead pipe (85 mg for 50% Pb-downstream versus 83 mg for -Pb) due to galvanic and deposition corrosion. The partially replaced service line configuration also had a much greater likelihood of producing water with #spikes# of lead particulates at higher flow rates, while tending to produce lower levels of lead at very low flow rates. After the first 214 days the galvanic current between copper and lead was only reduced by 34%, proving that galvanic impacts can be highly persistent even in water with optimized corrosion control by dosing of zinc orthophosphate. Finally, this experiment raises concern about the low flow rates used during some prior home sampling events, which may underestimate exposure to lead during normal water use, especially when galvanic Pb:Cu connections are present.

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