Using the Lead and Copper Rule Revisions Five-Sample Approach to Identify Schools with Increased Lead in Drinking Water Risks

Despite public concern, the risk of lead exposure from schools remains poorly understood. The Lead and Copper Rule Revisions (LCRR) include, for the first time, a five-sample lead testing requirement for all elementary schools. However, the United States Environmental Protection Agency does not define school-wide lead risk or provide clear guidance on how results should be interpreted. Using the Massachusetts Lead in School Drinking Water Database, we explored the application of the LCRR sampling approach and provide insight into the magnitude and distribution of lead in water in Massachusetts public schools. We observed that 12% of fixtures had first draw lead >15 ppb and 3% after a 30 s flushing. Approximately 90% of fixtures with lead >15 ppb were clustered in 34% of schools. We determined a school-wide 90th percentile of 10 ppb closely approximated this clustering of problem fixtures and were able to identify schools with problem fixtures using the five-sample results with a confidence >90%. Fixtures releasing lead >1 ppb occurred in >90% of schools and represented 58% of first draws and 33% of 30-s flushed samples. Overall, our study provides an approach to classify a school's lead risk, which could help water utilities and schools prioritizing testing and remediation efforts.