Desktop guidance for mitigating Pb and Cu corrosion by‐products

Abstract

Desktop studies accurately predict trends in corrosion by‐product release. Utility experiences were examined to assess the reliability of solubility models and decision trees in forecasting control of lead (Pb) and copper (Cu) corrosion by‐products. Such approaches cannot quantitatively predict effectiveness of corrosion control. For example, even the best‐fit solubility models explain only about 35 and 18 percent of the quantitative variation in 90th percentile Cu and Pb release, respectively. However, the decision trees and solubility models are qualitatively consistent with utility experience and are thus useful when promising water quality changes are identified to mitigate corrosion by‐product release. Utility experiences confirm that an optimal alkalinity range (20–40 mg/L as CaCO3) exists for Pb corrosion control above pH 8.5, a higher mass ratio of chloride to sulfate tends to worsen Pb by‐product release, and detectable color can signal a natural organic material content that may adversely affect compliance with the Cu action limit.

Factors influencing lead and iron release from some Egyptian drinking water pipes

“…A review of lead levels reported by 365 water utilities, following the implementation of the U.S. EPA Lead and Copper Rule, carried out by Edwards et al [21] revealed that higher Cl − :SO 4 −− ratios were associated with higher 90th-percentile lead levels at the consumer's tap. The study showed that 100% of the utilities that delivered drinking water with Cl − :SO 4 −− ratio below 0.58 met the U.S. EPA's action level for lead of 0.015 mg/l.…”

Impact of treatment on Pb release from full and partially replaced harvested Lead Service Lines (LSLs)

“…The supplied water could be considered as a medium risk of corrosion due to its relatively high alkalinity of 83 mg CaCO 3 /L and pH of 7.7 (Edwards et al, 1999). However, the CSMR value of 0.9 is considered for significant risk of galvanic corrosion (Nguyen et al, 2011b).…”

Role of iron and aluminum coagulant metal residuals and lead release from drinking water pipe materials

“…For example, higher chloride:sulfate mass ratios (CSMR) resulting from switches from sulfate-containing coagulant to chloride-containing have triggered several instances of elevated lead release from galvanic corrosion in service lines and premise plumbing. [2][3][4][5][6][7][8][9] It is also accepted that the removal of natural organic matter (NOM) via coagulation and other water treatment steps can strongly influence lead release and metal corrosion through a variety of mechanisms. [10][11][12][13][14] One prior research article also attempted to quantify possible secondary benefits of aluminum from coagulation passing through water treatment (i.e., residual aluminum) in reducing lead release, but instead demonstrated that the aluminum tended to increase mobilization of lead.…”