U.S. public water systems
Every active public water system regulated under the Safe Drinking Water Act, catalogued from EPA SDWIS/ECHO records — one public-record page per system.
Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.
Active systems
143,021
Population served
352M
Groundwater share
90.4%
Surface-water share
9.6%
By system type
49,389
CWS
Community water system
17,040
NTNCWS
Non-transient non-community water system
76,592
TNCWS
Transient non-community water system
Largest systems nationwide
Full ranking →| # | Water system | State | County | Population served | Type | Source |
|---|---|---|---|---|---|---|
| 1 | New York City System | New York | Richmond | 8,271,000 | Community | Surface water |
| 2 | Los Angeles-City, Dept. of Water & Power | California | Los Angeles | 7,751,132 | Community | Surface water |
| 3 | City of Houston | Texas | Harris | 2,970,543 | Community | Surface water |
| 4 | Chicago | Illinois | Cook | 2,746,388 | Community | Surface water |
| 5 | MWRA | Massachusetts | Suffolk | 2,660,000 | Community | Surface water |
| 6 | Mdwasa - Main System | Florida | Miami-Dade | 2,377,460 | Community | Groundwater |
| 7 | San Antonio Water System | Texas | Bexar | 2,113,151 | Community | Purchased surface water |
| 8 | Washington Suburban Sanitary Commission | Maryland | Montgomery | 1,900,000 | Community | Surface water |
| 9 | Phoenix City of | Arizona | Maricopa | 1,695,000 | Community | Surface water |
| 10 | City of Baltimore | Maryland | Baltimore city | 1,600,000 | Community | Surface water |
Browse by state
Alabama579 systems · 6.3M servedAlaska1,321 systems · 864.3K servedArizona1,771 systems · 7.7M servedArkansas865 systems · 3.1M servedCalifornia7,892 systems · 46.6M servedColorado2,209 systems · 7.5M servedConnecticut2,362 systems · 2.9M servedDelaware494 systems · 1.1M servedDistrict of Columbia14 systems · 696.5K servedFlorida5,199 systems · 22.5M servedGeorgia2,370 systems · 10.7M servedHawaii137 systems · 1.5M servedIdaho1,950 systems · 1.8M servedIllinois4,585 systems · 12.6M servedIndiana3,975 systems · 5.8M servedIowa1,824 systems · 3.1M servedKansas1,034 systems · 2.9M servedKentucky437 systems · 5.1M servedLouisiana1,124 systems · 5.2M servedMaine1,866 systems · 937.4K servedMaryland3,074 systems · 6M servedMassachusetts1,631 systems · 10.3M servedMichigan10,597 systems · 9M servedMinnesota6,534 systems · 5.3M servedMississippi1,181 systems · 3.3M servedMissouri2,938 systems · 6M servedMontana2,382 systems · 1.2M servedNebraska1,328 systems · 1.8M servedNevada649 systems · 3.5M servedNew Hampshire2,443 systems · 1.2M servedNew Jersey3,505 systems · 9.6M servedNew Mexico1,189 systems · 2.2M servedNew York8,164 systems · 19.6M servedNorth Carolina5,325 systems · 9.9M servedNorth Dakota403 systems · 751.1K servedOhio4,028 systems · 11.1M servedOklahoma1,276 systems · 3.7M servedOregon2,527 systems · 4M servedPennsylvania7,243 systems · 12.6M servedRhode Island465 systems · 1.2M servedSouth Carolina1,392 systems · 4.8M servedSouth Dakota706 systems · 967K servedTennessee1,390 systems · 8M servedTexas7,076 systems · 33.2M servedUtah1,139 systems · 3.9M servedVermont1,356 systems · 646.2K servedVirginia2,733 systems · 7.9M servedWashington4,705 systems · 10.1M servedWest Virginia801 systems · 1.6M servedWisconsin11,053 systems · 5.2M servedWyoming776 systems · 649.9K served