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Lead in Drinking Water Map

Understanding Lead in Drinking Water

Lead is a toxic metal that can cause serious health problems, especially in children. Unlike many other contaminants, lead typically enters drinking water through corrosion of lead pipes, faucets, and fixtures in homes and buildings—not from the water source itself.

The EPA has set the Maximum Contaminant Level Goal (MCLG) for lead in drinking water at zero because lead can be harmful even at low exposure levels. However, lead pipes and service lines remain common in many US cities, particularly in older homes built before 1986.

Water systems test for lead at customers' taps under EPA's Lead and Copper Rule and report the 90th percentile of those samples. When the 90th percentile is above 15 ppb (0.015 mg/L), the action level, the system must take further steps. For each city's water system, this map shows the 90th percentile for the most recently reported sampling period against that level.

Health Effects of Lead Exposure

Lead exposure can cause serious health problems including:

  • Children: Developmental delays, learning difficulties, behavioral problems, lower IQ, and hearing problems
  • Pregnant women: Premature birth, reduced growth of the fetus, and potential harm to the developing nervous system
  • Adults: Cardiovascular effects, kidney problems, decreased kidney function, and reproductive issues

No level of lead exposure is known to be without harm. Even low levels can accumulate in the body over time, causing long-term health effects.

Data Sources & Limitations

Each city shows the lead 90th-percentile result for the most recently reported sampling period of the city's water system under the Lead and Copper Rule, from EPA's Safe Drinking Water Act data (2026 Q2, downloaded Jul 9, 2026), with its monitoring period and the date it was first reported to EPA. States sometimes re-submit an older period after a newer one; the older period does not replace the newer one. When the period has more than one result, the higher is shown. A monitoring period still in progress is shown as in progress. The water system is the one the city's water report shows by default.

3,629 of the 18,298 cities on the map are shown in grey. For 229 of them we don't hold the water system's EPA ID, so we can't show its EPA lead-and-copper result; for 83, EPA has no lead-and-copper result on file for the system; for 3,317, none of the systems we list for the city is its own in EPA's records. Each way that is a gap in the record we publish, not a finding about the water.

535 results come from a monitoring period that ended more than 10 years before EPA's data; they are labelled outdated and still shown with their dates. 2 are 1,000 ppb or more; they are not coloured by value but flagged as an implausible EPA record to confirm with the utility.

Important notes:

  • A 90th percentile summarizes one sampling period of a system's tap samples. It does not describe every tap, and some systems' most recently reported monitoring periods are years old
  • Lead typically enters water from pipes inside your home, not the water supply
  • Homes built before 1986 are more likely to have lead pipes and fixtures
  • Lead often comes from household plumbing, so testing at your own tap is the most direct way to know
  • Run your water for 30 seconds to 2 minutes before drinking, especially if water hasn't been used for several hours

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