Predictors of Water Lead Levels in Drinking Water of Homes With Domestic Wells in 3 Illinois Counties.

CONTEXT Millions of US homes receive water from private wells, which are not required to be tested for lead (Pb). An approach to prioritizing high-risk homes for water lead level (WLL) testing may help focus outreach and screening efforts, while reducing the testing of homes at low risk. OBJECTIVE To (1) characterize distribution of WLLs and corrosivity in tap water of homes with private residential wells, and (2) develop and evaluate a screening strategy for predicting Pb detection within a home. DESIGN Cross-sectional. SETTING Three Illinois counties: Kane (northern), Peoria (central), and Jackson (southern). PARTICIPANTS 151 private well users from 3 Illinois counties. INTERVENTION Water samples were analyzed for WLL and corrosivity. MAIN OUTCOME MEASURES (1) WLL and corrosivity, and (2) the sensitivity, specificity, and predictive value of a strategy for prioritizing homes for WLL testing. RESULTS Pb was detected (>0.76 ppb) in tap water of 48.3% homes, and 3.3% exceeded 15 ppb, the US Environmental Protection Agency action level for community water systems. Compared with homes built in/after 1987 with relatively low corrosivity, older homes with more corrosive water were far more likely to contain measurable Pb (odds ratio = 11.07; 95% confidence interval, 3.47-35.31). The strategy for screening homes with private wells for WLL had a sensitivity of 88%, specificity of 42%, positive predictive value of 58%, and negative predictive value of 80%. CONCLUSIONS Pb in residential well water is widespread. The screening strategy for prioritizing homes with private wells for WLL testing is greater than 85% sensitive.