Drinking-water safety · Population served
America's Largest City Water Systems
The biggest community water systems we profile, by population served — the utilities that deliver tap water to the most Americans.
Los Angeles leads "America's Largest City Water Systems" at 7,751,132 served.
| # | City | Population served |
|---|---|---|
| 1 | Los Angeles LOS ANGELES-CITY, DEPT. OF WATER & POWER | 7,751,132 served |
| 2 | Houston CITY OF HOUSTON | 2,970,543 served |
| 3 | Chicago CHICAGO | 2,746,388 served |
| 4 | Miami MDWASA - MAIN SYSTEM | 2,377,460 served |
| 5 | San Antonio SAN ANTONIO WATER SYSTEM | 2,113,151 served |
| 6 | Phoenix PHOENIX CITY OF | 1,695,000 served |
| 7 | Philadelphia PHILADELPHIA WATER DEPARTMENT | 1,600,000 served |
| 8 | Baltimore CITY OF BALTIMORE | 1,600,000 served |
| 9 | Las Vegas LAS VEGAS VALLEY WATER DISTRICT | 1,539,277 served |
| 10 | Oakland EAST BAY MUD | 1,442,800 served |
| 11 | San Diego SAN DIEGO, CITY OF | 1,385,379 served |
| 12 | Dallas DALLAS WATER UTILITY | 1,356,479 served |
| 13 | Cleveland CLEVELAND PUBLIC WATER SYSTEM | 1,308,955 served |
| 14 | Columbus COLUMBUS PUBLIC WATER SYSTEM | 1,305,946 served |
| 15 | Denver DENVER WATER BOARD | 1,287,000 served |
| 16 | Charlotte CHARLOTTE WATER | 1,163,701 served |
| 17 | Seattle SEATTLE PUBLIC UTILITIES | 1,161,961 served |
| 18 | Austin CITY OF AUSTIN WATER & WASTEWATER | 1,115,323 served |
| 19 | Atlanta ATLANTA | 1,089,893 served |
| 20 | San Jose SAN JOSE WATER | 1,039,920 served |
| 21 | Fort Worth CITY OF FORT WORTH | 955,900 served |
| 22 | Indianapolis CITIZENS WATER - INDIANAPOLIS | 880,345 served |
| 23 | Jacksonville JEA MAJOR GRID | 826,664 served |
| 24 | Nashville METRO WATER SERVICES | 778,153 served |
| 25 | Rochester MCWA | 768,458 served |
Source: EPA Safe Drinking Water Information System (SDWIS) · 2026 Q1 refresh; violations since 2016