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Lead in drinking water: a plain-English guide

Lead is a potent toxin with no safe level of exposure. It rarely originates in the source water; it leaches from corroding lead service lines, lead solder, brass fixtures, and older home plumbing as water sits in pipes. EPA's 2024 Lead and Copper Rule Improvements (LCRI) lowers the action level from 15 ppb to 10 ppb effective November 2027 and requires utilities to identify and replace lead service lines within 10 years.

Where lead in drinking water comes from

Lead is not a contaminant of source water. Reservoirs, rivers, and groundwater wells almost never contain lead in measurable amounts. Lead enters the water on the way to your tap, almost always from one of four places:

  • Lead service lines: the pipes that connect a water main to a home, installed widely from the late 1800s through the 1980s. Roughly 9 million U.S. homes are still connected to one.
  • Lead solder used to join copper pipes, banned for drinking-water use in 1986 but still present in older homes.
  • Brass plumbing fixtures: leaded brass was legal at up to 8% lead through 2014. The current federal standard caps weighted-average lead content of fixtures at 0.25%.
  • Galvanized service lines that previously sat downstream of lead pipes. They accumulate lead over decades and continue to release it after the lead pipe is replaced.

This is why a utility can show low lead at the treatment plant and an individual home can still test high: the lead is between them.

Why MCLG = 0

The Maximum Contaminant Level Goal for lead is zero. EPA’s position is that there is no level of lead exposure that is known to be safe. Lead is a developmental neurotoxin: even very low childhood blood lead levels are associated with reduced IQ, attention problems, and behavioral effects. In adults, chronic exposure is linked to elevated blood pressure, kidney disease, and cardiovascular events.

Pregnant people, infants, and children under six are the most sensitive populations. Lead crosses the placenta, and the developing brain absorbs lead more efficiently than the adult brain.

The 2024 Lead and Copper Rule Improvements (LCRI)

EPA finalized the LCRI in October 2024. Key provisions:

  • Mandatory lead service line replacement within 10 years for the vast majority of utilities. The 10-year clock generally starts November 1, 2027.
  • Lower action level: 10 ppb (0.010 mg/L), down from 15 ppb under the prior rule. Effective November 2027. If a utility’s 90th-percentile sample exceeds 10 ppb, it must take corrective action.
  • Public inventories: each system was required to publish a service line inventory by October 2024, classifying every line as lead, non-lead, galvanized-requiring-replacement, or unknown. Unknowns must be resolved.
  • School and child-care testing: utilities must offer testing at every elementary school and licensed child care facility.

The LCRI is the most consequential drinking-water rule change in a generation. Some industry groups have challenged components in court; the 10-year service-line replacement requirement has so far been upheld.

What to do if your home may have lead

  1. Find out what your service line is. Your utility’s inventory is public. The MyTapWater.us PWS page above links to it.
  2. Flush before drinking. If water has sat in pipes for more than six hours, run the cold tap for at least 30 seconds.
  3. Use cold water for cooking and drinking. Hot water dissolves lead more readily.
  4. Filter at the tap. Look for a filter certified to NSF/ANSI Standard 53 for lead reduction. Many under-sink, faucet-mount, and pitcher filters carry this certification. Verify the exact cartridge model on the NSF database, not just marketing language.
  5. Test your tap water. Many utilities and state health departments offer low-cost lead test kits. Sample first-draw water from a cold tap that has not been used overnight.

This page is general information and is not medical advice. If you are concerned about a specific exposure, especially for a pregnant person or a young child, talk to your clinician about a blood lead test.

Sources

Editorial review: reviewed 2026-05-11 by RK 2026-05-11. Editorial standards.