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
🔒 Create a free account to export CSV| # | Water system | County | Population served | Type | Source |
|---|---|---|---|---|---|
| 1 | San Diego, City of | San Diego | 1,385,379 | Community | Surface water |
| 2 | Helix Water District | San Diego | 277,668 | Community | Surface water |
| 3 | Otay Water District | San Diego | 238,008 | Community | Purchased surface water |
| 4 | Sweetwater Authority | San Diego | 191,282 | Community | Surface water |
| 5 | Oceanside, City of | San Diego | 171,483 | Community | Purchased surface water |
| 6 | Escondido, City of | San Diego | 137,044 | Community | Surface water |
| 7 | Vista Irrigation District | San Diego | 132,430 | Community | Surface water |
| 8 | Vallecitos Wd | San Diego | 113,500 | Community | Purchased surface water |
| 9 | Cal-Am Water Coronado | San Diego | 106,000 | Community | Purchased surface water |
| 10 | Carlsbad Mwd | San Diego | 95,158 | Community | Purchased surface water |
| 11 | Padre Dam Mwd | San Diego | 93,980 | Community | Purchased surface water |
| 12 | Olivenhain Mwd | San Diego | 86,458 | Community | Purchased surface water |
| 13 | Poway, City of | San Diego | 49,888 | Community | Surface water |
| 14 | Camp Pendleton (South) | San Diego | 42,219 | Community | Groundwater |
| 15 | San Dieguito Wd | San Diego | 40,405 | Community | Purchased surface water |
| 16 | Ramona Municipal Wd | San Diego | 37,047 | Community | Purchased surface water |
| 17 | Nas North Island & Nab Coronado | San Diego | 36,990 | Community | Purchased surface water |
| 18 | Pine Valley Border Patrol Station | San Diego | 36,604 | Non-transient non-community | Groundwater |
| 19 | Lakeside Wd | San Diego | 35,500 | Community | Purchased surface water |
| 20 | Fallbrook PUD | San Diego | 35,237 | Community | Purchased surface water |
| 21 | Rincon Del Diablo Mwd (Id-1) | San Diego | 30,757 | Community | Purchased surface water |
| 22 | Valley Center Mwd | San Diego | 29,938 | Community | Purchased surface water |
| 23 | Yoga Center Mother'S Kitchen | San Diego | 27,884 | Transient non-community | Groundwater |
| 24 | San Diego Mountain Lodge | San Diego | 26,641 | Transient non-community | Groundwater |
| 25 | Dhs Border Patrol Hwy 94 Checkpoint | San Diego | 25,083 | Non-transient non-community | Groundwater under influence of surface water |
| 26 | Auerbach Farms | San Diego | 25,068 | Non-transient non-community | Groundwater |
| 27 | Rainbow Municipal Wd | San Diego | 23,536 | Community | Purchased surface water |
| 28 | Santa Fe I.D. | San Diego | 21,578 | Community | Surface water |
| 29 | Dhs Boulevard Border Patrol | San Diego | 20,270 | Non-transient non-community | Groundwater |
| 30 | South Bay Rod & Gun Club Inc.. | San Diego | 18,900 | Transient non-community | Groundwater |
| 31 | Palomar Christian Conference Center | San Diego | 13,050 | Community | Groundwater |
| 32 | Indian Hills Camp | San Diego | 13,032 | Community | Groundwater |
| 33 | Camp Pendleton (North) | San Diego | 12,651 | Community | Groundwater |
| 34 | Lake Henshaw Resort Inc.. | San Diego | 9,913 | Community | Groundwater |
| 35 | Warner Springs Ranch Resort LLC | San Diego | 4,831 | Non-transient non-community | Groundwater |
| 36 | Palomar Observatory | San Diego | 4,416 | Community | Groundwater |
| 37 | Mataguay Scout Reservation | San Diego | 4,000 | Transient non-community | Groundwater |
| 38 | Del Mar, City of | San Diego | 3,919 | Community | Purchased surface water |
| 39 | Bandy Canyon Ranch Corp | San Diego | 3,564 | Transient non-community | Groundwater |
| 40 | Borrego Wd | San Diego | 3,429 | Community | Groundwater |
| 41 | Rincon Del Diablo Mwd (Id-A) | San Diego | 3,275 | Community | Purchased surface water |
| 42 | Cuyamaca Water District | San Diego | 2,923 | Community | Groundwater |
| 43 | Pine Valley Mutual Wc | San Diego | 2,645 | Community | Groundwater |
| 44 | Schoepe Scout Reservation at Lost Valley | San Diego | 2,500 | Transient non-community | Groundwater |
| 45 | Majestic Pines Community Sd | San Diego | 1,768 | Community | Groundwater |
| 46 | Julian Community Services District | San Diego | 1,517 | Community | Groundwater |
| 47 | De Anza Springs Resort | San Diego | 1,000 | Transient non-community | Groundwater |
| 48 | Mountain Empire High School | San Diego | 1,000 | Non-transient non-community | Groundwater |
| 49 | Rancho Pauma Mutual Wc | San Diego | 899 | Community | Groundwater |
| 50 | Descanso Community Water District | San Diego | 870 | Community | Groundwater |
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.
- William Heise County Park850
- Usn San Clemente Island800
- Yuima Municipal Water District Ida769
- Pine Hills Mutual Water Company760
- Cuyamaca Sp - Paso Picacho691
- Lake Morena'S Oak Shores Mwc670
- Stagecoach Trails Rv Resort600
- Mount Laguna Improvement Assn.578
- Jacumba Community Sd561
- Campo Hills-County Public Works Wastewtr500
- Cuyamaca Outdoor School500
- Mount Laguna Water System500
- Rough Acres Foundation497
- Anza Borrego Sp - Palm Canyon484
- Warner Springs Estates448
- Thousand Trails Oakzanita Inc..404
- Pinezanita Inc..400
- Twin Lakes Resort400
- Agua Caliente County Park400
- Gsa Tecate Port of Entry400
- Yuima Municipal Water District360
- Lake Morena Views Mwc360
- Butterfield Ranch353
- Ymca Camp Marston/Raintree338
- Del Dios Mutual Water Company330
- Live Oak Springs Water System317
- Campo Elementary School300
- City of San Diego - El Capitan Reservoir300
- Lake Morena County Park300
- Sutherland Reservoir Recreation Area300
- Potrero Elementary School300
- Heavenly Oaks300
- Barrett Lake Mh and Rv LLC300
- San Pasqual Academy298
- North Peak Mutual Water Company298
- Rancho Del Campo Water System290
- Cuyamaca Sp - Green Valley266
- Oakvale Park260
- Pine Valley Bible Conference Center255
- Warner Unified School District250
- Camp Winacka250
- Ramona Oaks Rv Resort250
- Lake Wohlford Resort250
- Whispering Oaks Program Center250
- Santa Ysabel Nature Center248
- Los Tules Mutual Water Company238
- Freedom Ranch235
- The Oaks Venture, LLC220
- Tecate Vista Mutual Water Company204
- Yoga Center Retreat201
- Daley Ranch200
- Louis A. Stelzer County Park200
- Rancho Estates Mutual Water Co.200
- Pine Valley Trailer Park200
- Hodges Reservoir Recreation Area200
- City of San Diego, Camp Morena200
- Palomar Mountain Mutual Water Co.193
- Alpine Oaks Estates LLC185
- Pauma Valley Water Company185
- Banner Small Water Company175
- Whispering Winds Catholic Conference Cen162
- Usn Camp Michael Monsoor160
- Dhs Border Patrol I-8 Checkpoint160
- Clover Flat Elementary School160
- Jess Martin County Park150
- Mobiland Camper Park150
- Sunrise Estates Mutual Water Company150
- Vallecito County Park145
- Palomar Mtn. Sp - Silvercrest143
- Lazy H Mutual Water Company142
- Wynola Water District140
- Palomar Mtn. Sp - Doane Valley131
- Diamond Jack'S Rv Ranch127
- Quiet Oaks Mobile Home Park120
- Nd Daniel'S Investment LLC106
- Rancho Santa Teresa Mw Co.102
- Calvary Chapel Julian101
- Willowside Terrace Water Association100
- Descanso Junction100
- Alpine American Legion100
- Canebrake County Water District100
- El Monte County Park100
- Potrero County Park100
- Nickel Beer Water Company100
- Guatay Mutual Benefit Corporation100
- Laguna Mountain Mutual Water Co.100
- Ocotillo Oasis, LLC96
- Wynola Farms Water District84
- Camp Stevens78
- Santa Margarita County Preserve75
- Potrero General Store75
- Julian Oaks Camp72
- All Saints Retreat and Formation Center72
- Camp Denver Fox71
- Muir Industries Inc..70
- Leapin' Lizard Rv Ranch70
- Pinecrest70
- Oak Grove Complex68
- Oak Knoll Village66
- Fry Creek / Observatory66
- Usn Sere Camp Warner Springs65
- La Cima Fire Center60
- Camp Cedar Glen60
- Ocotillo Wells Svra - Hq50
- Cameron Corners50
- Boulevard Koa Drinking Water50
- East County Transitional Living Center50
- Anza Borrego Sp - Tamarisk Grove50
- Campo Group LLC50
- Sycamore Canyon / Goodan Ranch50
- Calexico Lodge50
- Lux Inn47
- Ocotillo Wells Rv Park & Store47
- Questhaven Municipal Water District46
- Rancho Corte Madera, Inc..46
- Skyline Ranch Rv Park & Campground45
- San Pasqual Battlefield State Park44
- Spencer Valley School District40
- Pine Hill Egg Ranch40
- Descanso Fire Station34
- Camp Lockett Middle School34
- Anza Borrego Sp - Vallecito31
- Sacred Mountain Inn30
- Caltrans, Tecate Cvef30
- Jacumba Valley Ranch Water Company30
- San Ysidro Health - Mhfm30
- Richardson Beardsley Park Inc..28
- Puerta La Cruz Cc #1427
- Anza Borrego Sp - Horse Camp26
- Desert Ironwoods Resort Inc..25
- Tecate Supermarket25
- Apple Water Is Good25
- Caltrans, Buckman Springs Rest Area25
- Ocotillo Wells - Holmes Camp25
- Oakoasis Open Space Preserve25
- Cibbetts Flats Campground25
- Fallbrook Kamp Retreat24
- Boulevard Pines Mobile Home and Rv Park18
- Rey River Ranch Corp.12
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
- All California public water systems· 7,479 active
- Los Angeles County· 275 systems
- Tulare County· 274 systems
- Madera County· 202 systems
- Riverside County· 197 systems
- Stanislaus County· 191 systems
- Napa County· 188 systems
- How to find out who supplies your drinking water
- How to find and read your annual water quality report
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).