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
142,891
Population served
349.3M
Groundwater share
90.4%
Surface-water share
9.6%
By system type
49,378
CWS
Community water system
17,037
NTNCWS
Non-transient non-community water system
76,476
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 + 4 more | 8,271,000 | Community | Surface water |
| 2 | Los Angeles-City, Dept. of Water & Power | California | Los Angeles | 3,875,566 | Community | Surface water |
| 3 | City of Houston | Texas | Harris | 2,970,543 | Community | Surface water |
| 4 | Chicago | Illinois | Cook | 2,721,308 | Community | Surface water |
| 5 | San Antonio Water System | Texas | Bexar | 2,643,729 | Community | Purchased surface water |
| 6 | MWRA | Massachusetts | Suffolk | 2,580,000 | Community | Surface water |
| 7 | Mdwasa - Main System | Florida | Miami-Dade | 2,377,460 | Community | Groundwater |
| 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
Alabama576 systems · 6.4M servedAlaska1,322 systems · 862.9K servedArizona1,769 systems · 7.7M servedArkansas853 systems · 3.1M servedCalifornia7,479 systems · 42.7M servedColorado2,207 systems · 7.5M servedConnecticut2,363 systems · 2.9M servedDelaware494 systems · 1.1M servedDistrict of Columbia12 systems · 697.4K servedFlorida5,197 systems · 22.6M servedGeorgia2,375 systems · 10.7M servedHawaii136 systems · 1.5M servedIdaho1,961 systems · 1.8M servedIllinois3,872 systems · 12.4M servedIndiana3,969 systems · 5.8M servedIowa1,828 systems · 3.1M servedKansas1,041 systems · 2.9M servedKentucky437 systems · 5.1M servedLouisiana1,121 systems · 5.3M servedMaine1,862 systems · 937.2K servedMaryland2,992 systems · 5.8M servedMassachusetts1,636 systems · 10.3M servedMichigan10,599 systems · 9M servedMinnesota6,465 systems · 5.3M servedMississippi1,133 systems · 3.2M servedMissouri2,943 systems · 6M servedMontana2,378 systems · 1.2M servedNebraska1,226 systems · 1.8M servedNevada643 systems · 3.5M servedNew Hampshire2,450 systems · 1.2M servedNew Jersey3,496 systems · 9.6M servedNew Mexico1,165 systems · 2.2M servedNew York8,167 systems · 19.4M servedNorth Carolina5,087 systems · 10M servedNorth Dakota403 systems · 751.4K servedOhio3,854 systems · 10.7M servedOklahoma1,254 systems · 3.6M servedOregon2,536 systems · 4M servedPennsylvania7,217 systems · 12.6M servedRhode Island465 systems · 1.2M servedSouth Carolina1,392 systems · 4.9M servedSouth Dakota699 systems · 969.2K servedTennessee1,383 systems · 8M servedTexas7,078 systems · 33.9M servedUtah1,133 systems · 3.9M servedVermont1,357 systems · 647.1K servedVirginia2,420 systems · 7.6M servedWashington4,705 systems · 10.2M servedWest Virginia791 systems · 1.6M servedWisconsin11,056 systems · 5.2M servedWyoming775 systems · 649.6K served
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