Profile Sampling To Characterize Particulate Lead Risks in Potable Water

Abstract

Traditional lead (Pb) profiling, or collecting sequential liters of water that flow from a consumer tap after a stagnation event, has recently received widespread use in understanding sources of Pb in drinking water and risks to consumer health, but has limitations in quantifying particulate Pb risks. A new profiling protocol was developed in which a series of traditional profiles are collected from the same tap at escalating flow rates. The results revealed marked differences in risks of Pb exposure from one consumer home to another as a function of flow rate, with homes grouped into four risk categories with differing flushing requirements and public education to protect consumers. On average, Pb concentrations detected in water at high flow without stagnation were at least three to four times higher than in first draw samples collected at low flow with stagnation, demonstrating a new "worst case" lead release scenario, contrary to the original regulatory assumption that stagnant, first draw samples contain the highest lead concentrations. Testing also revealed that in some cases water samples with visible particulates had much higher Pb than samples without visible particulates, and tests of different sample handling protocols confirmed that some EPA-allowed methods would not quantify as much as 99.9% of the Pb actually present (avg. 27% of Pb not quantified).

Ion-Selective Electrodes for Detection of Lead (II) in Drinking Water: A Mini-Review

“…A number of studies have indicated that significant contributions of particulate-associated lead can be mobilized as a function of flow rate and turbulence in certain water chemistries [94][95][96][97]. Lead-selective ISE sensors are not capable of detecting particulate lead.…”

Increased Lead in Water Associated with Iron Corrosion

“…Exactly how particulate lead is formed and released to water is relatively poorly understood, and quantification of this problem is highly sensitive to nuances of sampling, including the flow rate during sampling (Reiber et al, 1997;Triantafyllidou and Edwards, 2012;Clark et al, 2014). Obviously, the durability and adherence of lead rust/scale to pipes is one key factor, although as a practical matter little is known about factors that control these characteristics (McNeill and Edwards, 2004).…”

Monitoring of heavy metals in selected Water Supply Systems in Poland, in relation to current regulations

“…In the case of heavy metals monitoring, it's very important to take into account the accumulation of them in human organisms. That is why monitoring of heavy metals should be carried out in accordance with other principles which take into account the process of metal accumulation in consumer organisms [14][15][16][17][18][19][20][21][22]. The approach to this problem in Poland is fundamentally different from the proper approach, which may give a true picture of water quality in the network.…”

“…Water supply companies and sanitary inspection focus only on aspects shown if water quality meets the guidelines outlined in the Regulation of the Polish Minister of Health, the frequency and optimal localization of monitoring points aren't important for them. [15,19,21,22]. In the United States, the EPA recommends an individual approach to monitoring of heavy metals for which separate recommendations have been made.…”

“…There are several methods to design it [18,19,30]. In Polish regulations, the quantity of taken water samples is dependent on average of daily water production and whether a concrete water quality parameter has been qualified for check or audit monitoring.…”