Lead pipe rankings

National lists built from EPA SDWIS service line inventory, 2026 Q3. Free to cite with a link.

• The 100 U.S. water systems with the most lead service lines

  Chicago leads with 360,857 lead and galvanized service lines. The 100 U.S. water systems with the most lead pipes, from EPA inventory data.

• Water systems where the highest share of pipes are lead

  In some U.S. water systems most service lines are lead. The 100 systems (5,000+ lines) with the highest share of lead and galvanized lines, versus 3.1% nationally.

• Water systems with the most service lines of unknown material

  Millions of U.S. service lines are still "lead status unknown." The 100 water systems with the most unidentified lines, from EPA inventory data.

• Lead pipes in America’s 100 largest water systems

  67 of the 100 largest U.S. water systems reported confirmed lead or galvanized service lines. See each one's count.

• Water systems whose latest lead test exceeded the action level

  496 community water systems' most recent lead sampling exceeded the 15 ppb action level in EPA data. 139 also reported lead service lines.

• Water systems with the highest recent lead test results

  The 100 U.S. water systems (1,000+ people) with the highest 90th-percentile lead results in sampling periods since 2024, from EPA Lead and Copper Rule data.

• Water systems with the most health-based lead rule violations

  U.S. water systems with the most health-based Lead and Copper Rule violations since 2015, such as corrosion control and public education failures, from EPA records.

• Biggest drops in reported lead pipes since 2025 Q1

  The 100 U.S. water systems whose reported lead and galvanized service lines fell the most between 2025 Q1 and 2026 Q3, from quarterly EPA inventory data.

• America’s lead pipes in 2026: national data report

  Key findings, state charts and how system size affects unknown lines.

• Lead service lines by state

  Illinois leads with 667,350 lead and galvanized lines. Every state compared.