Orange County, California — public water systems

At a glance

46 active public water systems are filed under Orange County, California in EPA's SDWIS records, together reporting 3,201,893 people served. The largest is Irvine Ranch Water District, which reports serving 444,800 people. 40 are community water systems serving people where they live; the other 6 are non-community systems, such as schools, workplaces, campgrounds and gas stations with their own supply.

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

Active systems

Population served

3.2M

Community systems

Groundwater share

21.7%

How does Orange County compare with other California counties?

Orange County has the 47th-most active public water systems among the 201 counties listed for active California systems in EPA records; among the 72 with 3 or more systems, the median has 73. Its systems report 3,201,893 people served in total, the 3rd-largest county figure in the state and 7.5% of the statewide total. The average system here reports serving 69,606 people, about 12 times the California average of 5,706. Population figures are what each system reports; people served by more than one system, such as a wholesaler and the town that buys from it, are counted by each.

Where does Orange County's drinking water come from?

By primary water source, Orange County's active systems draw on purchased surface water (34, 74%), groundwater (10, 22%) and surface water (2, 4.3%). Overall, 22% rely mainly on groundwater (including purchased groundwater) and 78% on surface water, compared with 85% and 15% across California. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. The county's largest system, Irvine Ranch Water District, draws primarily on surface water.

What kinds of water systems operate in Orange County?

Orange County's active systems break down as 40 community systems (87%), 4 non-transient non-community systems (8.7%) and 2 transient non-community systems (4.3%). A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. EPA lists their owner types as local government (74%) and private (26%).

Water systems in Orange County

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Active public water systems in Orange County, California
#	Water system	County	Population served	Type	Source
1	Irvine Ranch Water District	Orange	444,800	Community	Surface water
2	City of Anaheim	Orange	348,593	Community	Surface water
3	City of Santa Ana	Orange	310,539	Community	Purchased surface water
4	City of Huntington Beach	Orange	201,000	Community	Purchased surface water
5	City of Garden Grove	Orange	174,226	Community	Purchased surface water
6	Moulton Niguel Water District	Orange	170,236	Community	Purchased surface water
7	Santa Margarita Water District	Orange	168,289	Community	Purchased surface water
8	City of Fullerton	Orange	139,461	Community	Purchased surface water
9	City of Orange	Orange	120,770	Community	Purchased surface water
10	Golden State Wc - West Orange County	Orange	114,379	Community	Purchased surface water
11	Mesa Water District	Orange	110,000	Community	Purchased surface water
12	City of Westminster	Orange	90,911	Community	Purchased surface water
13	Yorba Linda Water District	Orange	84,292	Community	Purchased surface water
14	City of Buena Park	Orange	81,998	Community	Purchased surface water
15	City of Newport Beach	Orange	68,572	Community	Purchased surface water
16	City of Tustin	Orange	66,600	Community	Purchased surface water
17	City of La Habra	Orange	63,118	Community	Purchased surface water
18	City of Fountain Valley	Orange	56,747	Community	Purchased surface water
19	El Toro Water District	Orange	51,800	Community	Purchased surface water
20	City of San Clemente	Orange	51,545	Community	Purchased surface water
21	Golden State Wc - Placentia/Yorba Linda	Orange	50,381	Community	Purchased surface water
22	City of Brea	Orange	48,479	Community	Purchased surface water
23	South Coast Water District	Orange	41,118	Community	Purchased surface water
24	Santa Margarita Water District-Id9	Orange	39,684	Community	Purchased surface water
25	City of Seal Beach	Orange	24,937	Community	Purchased surface water
26	Laguna Beach County Wd	Orange	18,404	Community	Purchased surface water
27	City of La Palma	Orange	15,948	Community	Purchased surface water
28	Trabuco Canyon Water District	Orange	13,659	Community	Purchased surface water
29	Golden State Wc - Cowan Heights	Orange	6,997	Community	Purchased surface water
30	Serrano Water District	Orange	5,659	Community	Purchased surface water
31	Joint Regional Water Supply System	Orange	3,947	Community	Purchased surface water
32	East Orange County Wd - Rz	Orange	3,464	Community	Purchased surface water
33	Knott S Berry Farm	Orange	3,000	Non-transient non-community	Purchased surface water
34	Eastside Water Association	Orange	2,000	Community	Groundwater
35	Smwd-Nichols Institute	Orange	1,600	Non-transient non-community	Purchased surface water
36	Los Alamitos Race Course	Orange	1,600	Non-transient non-community	Groundwater
37	Midway City Mutual Wc	Orange	1,305	Community	Groundwater
38	South Midway City Mutual Water Co.	Orange	891	Community	Groundwater
39	Canyon Rv Park	Orange	294	Non-transient non-community	Groundwater
40	Caspers Regional Wilderness Park	Orange	215	Transient non-community	Groundwater
41	Hynes Estates Mutual Water Co.	Orange	168	Community	Groundwater
42	Page Avenue Mutual Water Company	Orange	119	Community	Purchased surface water
43	Liberty Park Water Association	Orange	85	Community	Groundwater
44	Lazy W Ranch Water System	Orange	63	Transient non-community	Groundwater

Orange County water systems: frequently asked questions

How many public water systems are in Orange County, California?

EPA's SDWIS records file 46 active public water systems under Orange County, California: 40 community systems (87%), 4 non-transient non-community systems (8.7%) and 2 transient non-community systems (4.3%).

Who supplies drinking water in Orange County, CA?

The largest community water systems filed under Orange County are Irvine Ranch Water District (444,800 people served), City of Anaheim (348,593 people served) and City of Santa Ana (310,539 people served). Which system serves a particular address depends on its service area, which EPA's SDWIS records do not include; a water bill or the local utility can confirm it.

Does Orange County's drinking water come from groundwater or surface water?

Of the 46 active public water systems in Orange County, 22% draw mainly on groundwater and 78% on surface water, counting purchased supplies. The largest system, Irvine Ranch Water District, uses surface water.

Where can I find a water quality report for Orange County?

Each community water system must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1, covering the previous calendar year. 40 community systems are filed under Orange County, so the report to look for is the one from the system that supplies your address.

How can I check violations for a water system in Orange County?

Open the system's profile from the list on this page. Each profile shows the most recent Safe Drinking Water Act violations in EPA's records, with plain-English labels and whether each one is resolved. For current compliance status, EPA ECHO is the primary source.

More California water systems

About this data

Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.

Cite as: AquaCensus, “Public water systems in Orange County, California”, https://aquacensus.com/water-systems/california/orange (data as of October 1, 2026).