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San Diego County, California — public water systems

At a glance

191 active public water systems are filed under San Diego County, California in EPA's SDWIS records, together reporting 3,710,459 people served. The largest is City of San Diego, which reports serving 1,385,379 people. 79 are community water systems serving people where they live; the other 112 are non-community systems, such as schools, workplaces, campgrounds and gas stations with their own supply.

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

Active systems

191

Population served

3.7M

Community systems

79

Groundwater share

83.8%

How does San Diego County compare with other California counties?

San Diego County has the 11th-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 3,710,459 people served in total, the 2nd-largest county figure in the state and 8.7% of the statewide total. The average system here reports serving 19,427 people, about 3.4 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 San Diego County's drinking water come from?

By primary water source, San Diego County's active systems draw on groundwater (157, 82%), purchased surface water (21, 11%), surface water (10, 5.2%) and groundwater under influence of surface water (3, 1.6%). Overall, 84% rely mainly on groundwater (including purchased groundwater) and 16% on surface water, compared with 85% and 15% across California. Groundwater means the system draws its water from wells or springs fed by underground aquifers. The county's largest system, City of San Diego, draws primarily on surface water.

What kinds of water systems operate in San Diego County?

San Diego County's active systems break down as 79 community systems (41%), 22 non-transient non-community systems (12%) and 90 transient non-community systems (47%). 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 private (53%), local government (30%), federal government (8.4%) and state government (8.4%).

The 50 largest water systems in San Diego County

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Active public water systems in San Diego County, California
#Water systemCountyPopulation servedTypeSource
1San Diego, City ofSan Diego1,385,379CommunitySurface water
2Helix Water DistrictSan Diego277,668CommunitySurface water
3Otay Water DistrictSan Diego238,008CommunityPurchased surface water
4Sweetwater AuthoritySan Diego191,282CommunitySurface water
5Oceanside, City ofSan Diego171,483CommunityPurchased surface water
6Escondido, City ofSan Diego137,044CommunitySurface water
7Vista Irrigation DistrictSan Diego132,430CommunitySurface water
8Vallecitos WdSan Diego113,500CommunityPurchased surface water
9Cal-Am Water CoronadoSan Diego106,000CommunityPurchased surface water
10Carlsbad MwdSan Diego95,158CommunityPurchased surface water
11Padre Dam MwdSan Diego93,980CommunityPurchased surface water
12Olivenhain MwdSan Diego86,458CommunityPurchased surface water
13Poway, City ofSan Diego49,888CommunitySurface water
14Camp Pendleton (South)San Diego42,219CommunityGroundwater
15San Dieguito WdSan Diego40,405CommunityPurchased surface water
16Ramona Municipal WdSan Diego37,047CommunityPurchased surface water
17Nas North Island & Nab CoronadoSan Diego36,990CommunityPurchased surface water
18Pine Valley Border Patrol StationSan Diego36,604Non-transient non-communityGroundwater
19Lakeside WdSan Diego35,500CommunityPurchased surface water
20Fallbrook PUDSan Diego35,237CommunityPurchased surface water
21Rincon Del Diablo Mwd (Id-1)San Diego30,757CommunityPurchased surface water
22Valley Center MwdSan Diego29,938CommunityPurchased surface water
23Yoga Center Mother'S KitchenSan Diego27,884Transient non-communityGroundwater
24San Diego Mountain LodgeSan Diego26,641Transient non-communityGroundwater
25Dhs Border Patrol Hwy 94 CheckpointSan Diego25,083Non-transient non-communityGroundwater under influence of surface water
26Auerbach FarmsSan Diego25,068Non-transient non-communityGroundwater
27Rainbow Municipal WdSan Diego23,536CommunityPurchased surface water
28Santa Fe I.D.San Diego21,578CommunitySurface water
29Dhs Boulevard Border PatrolSan Diego20,270Non-transient non-communityGroundwater
30South Bay Rod & Gun Club Inc..San Diego18,900Transient non-communityGroundwater
31Palomar Christian Conference CenterSan Diego13,050CommunityGroundwater
32Indian Hills CampSan Diego13,032CommunityGroundwater
33Camp Pendleton (North)San Diego12,651CommunityGroundwater
34Lake Henshaw Resort Inc..San Diego9,913CommunityGroundwater
35Warner Springs Ranch Resort LLCSan Diego4,831Non-transient non-communityGroundwater
36Palomar ObservatorySan Diego4,416CommunityGroundwater
37Mataguay Scout ReservationSan Diego4,000Transient non-communityGroundwater
38Del Mar, City ofSan Diego3,919CommunityPurchased surface water
39Bandy Canyon Ranch CorpSan Diego3,564Transient non-communityGroundwater
40Borrego WdSan Diego3,429CommunityGroundwater
41Rincon Del Diablo Mwd (Id-A)San Diego3,275CommunityPurchased surface water
42Cuyamaca Water DistrictSan Diego2,923CommunityGroundwater
43Pine Valley Mutual WcSan Diego2,645CommunityGroundwater
44Schoepe Scout Reservation at Lost ValleySan Diego2,500Transient non-communityGroundwater
45Majestic Pines Community SdSan Diego1,768CommunityGroundwater
46Julian Community Services DistrictSan Diego1,517CommunityGroundwater
47De Anza Springs ResortSan Diego1,000Transient non-communityGroundwater
48Mountain Empire High SchoolSan Diego1,000Non-transient non-communityGroundwater
49Rancho Pauma Mutual WcSan Diego899CommunityGroundwater
50Descanso Community Water DistrictSan Diego870CommunityGroundwater

All other water systems in San Diego County (139)

The remaining active systems filed under San Diego County, largest first, with the population each reports serving.

San Diego County water systems: frequently asked questions

How many public water systems are in San Diego County, California?

EPA's SDWIS records file 191 active public water systems under San Diego County, California: 79 community systems (41%), 22 non-transient non-community systems (12%) and 90 transient non-community systems (47%).

Who supplies drinking water in San Diego County, CA?

The largest community water systems filed under San Diego County are City of San Diego (1,385,379 people served), Helix Water District (277,668 people served) and Otay Water District (238,008 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 San Diego County's drinking water come from groundwater or surface water?

Of the 191 active public water systems in San Diego County, 84% draw mainly on groundwater and 16% on surface water, counting purchased supplies. The largest system, City of San Diego, uses surface water.

Where can I find a water quality report for San Diego 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. 79 community systems are filed under San Diego 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 San Diego 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 San Diego County, California”, https://aquacensus.com/water-systems/california/san-diego (data as of October 1, 2026).