The 100 largest water systems in the United States

Ranked by reported population served in EPA SDWIS records. New York City System tops the list at 8,271,000 people served.

Dataset updated July 2026 . Source: EPA SDWIS/ECHO, refreshed quarterly.

The 100 largest active U.S. public water systems by population served
#	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
11	Philadelphia Water Department	Pennsylvania	Philadelphia	1,600,000	Community	Surface water
12	Las Vegas Valley Water District	Nevada	Clark	1,539,277	Community	Purchased surface water
13	East Bay MUD	California	Alameda	1,442,800	Community	Surface water
14	San Diego, City of	California	San Diego	1,385,379	Community	Surface water
15	Dallas Water Utility	Texas	Dallas	1,356,479	Community	Surface water
16	Cleveland Public Water System	Ohio	Cuyahoga	1,308,955	Community	Surface water
17	Columbus Public Water System	Ohio	Franklin	1,305,946	Community	Surface water
18	Denver Water Board	Colorado	Denver	1,287,000	Community	Surface water
19	Charlotte Water	North Carolina	Mecklenburg	1,163,701	Community	Surface water
20	Seattle Public Utilities	Washington	King	1,161,961	Community	Surface water
21	Fairfax County Water Authority	Virginia	Fairfax	1,121,613	Community	Surface water
22	City of Austin Water & Wastewater	Texas	Travis	1,115,323	Community	Surface water
23	Mo American St Louis St Charles Counties	Missouri	St. Louis	1,111,000	Community	Surface water
24	Suffolk County Water Authority	New York	Suffolk	1,100,000	Community	Groundwater
25	Atlanta	Georgia	DeKalb	1,089,893	Community	Surface water
26	Metropolitano	PR	San Juan Municipio	1,077,332	Community	Surface water
27	San Jose Water	California	Santa Clara	1,039,920	Community	Surface water
28	Gwinnett Co. Dept. of Water Resources	Georgia	Gwinnett	975,000	Community	Surface water
29	City of Fort Worth	Texas	Tarrant	955,900	Community	Surface water
30	Citizens Water - Indianapolis	Indiana	Marion	880,345	Community	Surface water
31	Sfpuc City Distribution Division	California	San Francisco	848,019	Community	Purchased surface water
32	Jea Major Grid	Florida	Duval	826,664	Community	Groundwater
33	Aqua Pa Main System	Pennsylvania	Montgomery	822,600	Community	Surface water
34	Veolia Water New Jersey Hackensack	New Jersey	Bergen	792,713	Community	Surface water
35	Metro Water Services	Tennessee	Davidson	778,153	Community	Surface water
36	Mcwa	New York	Orleans	768,458	Community	Surface water
37	Louisville Water Company	Kentucky	Jefferson	764,769	Community	Surface water
38	Cincinnati Public Water System	Ohio	Hamilton	750,200	Community	Surface water
39	El Paso Water Utilities Public Service B	Texas	El Paso	747,168	Community	Surface water
40	Dekalb County	Georgia	DeKalb	743,000	Community	Surface water
41	City of Tampa Water Department	Florida	Hillsborough	733,886	Community	Surface water
42	Tucson City of	Arizona	Pima	732,906	Community	Groundwater
43	Cobb County	Georgia	Cobb	695,000	Community	Purchased surface water
44	Pa Amer Water Co-Pittsburgh	Pennsylvania	Allegheny	686,000	Community	Surface water
45	Boston Water and Sewer Commission (MWRA)	Massachusetts	Suffolk	675,647	Community	Purchased surface water
46	Kentucky-American Water Co	Kentucky	Fayette	669,042	Community	Surface water
47	Eastern Municipal Wd	California	Riverside	666,581	Community	Purchased surface water
48	Portland Water Bureau	Oregon	Multnomah	666,200	Community	Surface water
49	Metropolitan Utilities District	Nebraska	Douglas	660,000	Community	Surface water
50	Memphis Light, Gas, & Water	Tennessee	Shelby	659,500	Community	Groundwater
51	Oklahoma City	Oklahoma	Oklahoma	644,000	Community	Surface water
52	Raleigh, City of	North Carolina	Wake	640,000	Community	Surface water
53	Detroit City of	Michigan	Wayne	633,218	Community	Purchased surface water
54	D.C. Water and Sewer Authority	District of Columbia	District of Columbia	632,323	Community	Purchased surface water
55	Hnl-Windward-Pearl Harbor	Hawaii	Honolulu	631,389	Community	Groundwater
56	Milwaukee Waterworks	Wisconsin	Milwaukee	626,000	Community	Surface water
57	Palm Beach County Water Utilities	Florida	Palm Beach	619,435	Community	Groundwater
58	Nj American Water - Raritan	New Jersey	Union	615,430	Community	Surface water
59	Baton Rouge Water Company	Louisiana	East Baton Rouge Parish	596,844	Community	Groundwater
60	Central Alabama Water System	Alabama	Jefferson	585,000	Community	Surface water
61	Albuquerque Water System	New Mexico	Bernalillo	560,326	Community	Surface water
62	City of Fresno	California	Fresno	545,716	Community	Surface water
63	Orlando Utilities Commission	Florida	Orange	536,466	Community	Groundwater
64	Aurora City of	Colorado	Arapahoe	533,407	Community	Surface water
65	City of Sacramento Main	California	Sacramento	527,979	Community	Surface water
66	Pittsburgh Water & Sewer Auth	Pennsylvania	Allegheny	520,000	Community	Surface water
67	Hcwrd/South-Central	Florida	Hillsborough	515,012	Community	Purchased surface water
68	Kansas City Pws	Missouri	Cass	513,800	Community	Surface water
69	Pinellas County Utilities	Florida	Pinellas	506,353	Community	Purchased surface water
70	Water District 1 of Johnson Co	Kansas	Johnson	490,000	Community	Surface water
71	Long Beach Utilities Department	California	Los Angeles	466,772	Community	Purchased surface water
72	Mesa City of	Arizona	Maricopa	466,000	Community	Surface water
73	Colorado Springs Utilities	Colorado	El Paso	464,111	Community	Surface water
74	Tacoma Water Division City of	Washington	Pierce	446,170	Community	Surface water
75	Irvine Ranch Water District	California	Orange	444,800	Community	Surface water
76	Truckee Meadows Water Authority	Nevada	Washoe	442,000	Community	Surface water
77	Virginia Beach, City of	Virginia	—	437,994	Community	Purchased surface water
78	North Fulton County	Georgia	Fulton	434,517	Community	Purchased surface water
79	Minneapolis	Minnesota	Hennepin	425,300	Community	Surface water
80	Regional Water Authority	Connecticut	New Haven	418,900	Community	Surface water
81	City of Arlington	Texas	Tarrant	413,955	Community	Surface water
82	Tulsa	Oklahoma	Tulsa	413,000	Community	Surface water
83	Newport News, City of	Virginia	—	407,300	Community	Surface water
84	Greenville Water (2310001)	South Carolina	Greenville	396,265	Community	Surface water
85	Wichita, City of	Kansas	Sedgwick	395,699	Community	Surface water
86	Saint Paul Regional Water Services	Minnesota	Ramsey	392,529	Community	Surface water
87	Metropolitan District Commission	Connecticut	Hartford	390,887	Community	Surface water
88	Chesterfield Co Central Water System	Virginia	Chesterfield	389,897	Community	Surface water
89	Winston-Salem, City of	North Carolina	Forsyth	388,060	Community	Surface water
90	Salt Lake City Water System	Utah	Salt Lake	381,174	Community	Surface water
91	Nj American Water - Coastal North	New Jersey	Monmouth	377,613	Community	Surface water
92	North Las Vegas Utilities	Nevada	Clark	376,515	Community	Purchased surface water
93	Vancouver City of	Washington	Clark	373,047	Community	Groundwater
94	Central Arkansas Water	Arkansas	Pulaski	368,455	Community	Surface water
95	Toledo City of	Ohio	Lucas	360,000	Community	Surface water
96	Aquarion-Eastern Fairfield County	Connecticut	Fairfield	351,756	Community	Surface water
97	Ocwa	New York	Onondaga	350,000	Community	Surface water
98	St Petersburg, City of	Florida	Pinellas	349,979	Community	Purchased surface water
99	City of Anaheim	California	Orange	348,593	Community	Surface water
100	Manatee County Utilities Dept	Florida	Manatee	347,800	Community	Surface water