Lead in Drinking Water
Lead contamination from aging pipes, solder, and fixtures, there is no safe level of lead exposure, and even low levels can cause irreversible developmental damage in children.
How It Works
Unlike most contaminants, lead typically enters drinking water from the customer's own plumbing, lead service lines (pipes connecting the water main to the home), lead solder on copper pipes, and brass fixtures. The EPA's Lead and Copper Rule requires water systems to test at customer taps and take action if the 90th percentile lead level exceeds 15 ppb (parts per billion). The revised Lead and Copper Rule (LCRI) of 2024 strengthens requirements and mandates replacement of all lead service lines within 10 years. An estimated 9.2 million lead service lines remain in use across the United States. The crisis in Flint, Michigan (2014-2019) brought national attention to lead in water when a switch in water sources caused lead to leach from aging pipes.
Related Terms
- Maximum Contaminant Level (MCL), The highest level of a contaminant allowed in drinking water, set by the EPA and enforceable by law. Exceeding the MCL triggers a health-based violation.
- Health-Based Violation, The most serious type of drinking water violation, indicating that water quality has exceeded a maximum contaminant level or failed to meet a treatment requirement that directly protects health.
- Action Level, A regulatory threshold that triggers required treatment or other corrective action when exceeded, used for lead (15 ppb) and copper (1.3 mg/L) instead of a traditional MCL.
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About This Definition
This definition is part of the IsWaterSafe Drinking Water Safety Glossary, 22 terms explaining water contaminants, treatment methods, and safety standards. Written for homeowners, renters, journalists, and public health professionals.