Santa Clara County, California — public water systems
At a glance
121 active public water systems are filed under Santa Clara County, California in EPA's SDWIS records, together reporting 2,097,447 people served. The largest is San Jose Water, which reports serving 1,039,920 people. 74 are community water systems serving people where they live; the other 47 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
121
Population served
2.1M
Community systems
74
Groundwater share
67.8%
How does Santa Clara County compare with other California counties?
Santa Clara County has the 20th-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 2,097,447 people served in total, the 7th-largest county figure in the state and 4.9% of the statewide total. The average system here reports serving 17,334 people, about 3 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 Santa Clara County's drinking water come from?
By primary water source, Santa Clara County's active systems draw on groundwater (80, 66%), purchased surface water (28, 23%), surface water (10, 8.3%) and purchased groundwater (2, 1.7%). Overall, 68% rely mainly on groundwater (including purchased groundwater) and 31% 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, San Jose Water, draws primarily on surface water.
What kinds of water systems operate in Santa Clara County?
Santa Clara County's active systems break down as 74 community systems (61%), 22 non-transient non-community systems (18%) and 25 transient non-community systems (21%). 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 (68%), local government (28%), state government (2.5%) and federal government (0.8%).
The 50 largest water systems in Santa Clara County
🔒 Create a free account to export CSV| # | Water system | County | Population served | Type | Source |
|---|---|---|---|---|---|
| 1 | San Jose Water | Santa Clara | 1,039,920 | Community | Surface water |
| 2 | City of Sunnyvale | Santa Clara | 157,566 | Community | Purchased surface water |
| 3 | City of Santa Clara | Santa Clara | 130,746 | Community | Purchased surface water |
| 4 | Great Oaks Wc Inc. | Santa Clara | 110,088 | Community | Groundwater |
| 5 | City of San Jose - Evg/Edv/Coy | Santa Clara | 101,265 | Community | Purchased surface water |
| 6 | City of Milpitas | Santa Clara | 81,773 | Community | Purchased surface water |
| 7 | City of Mountain View | Santa Clara | 81,501 | Community | Purchased surface water |
| 8 | Cwsc Los Altos Suburban | Santa Clara | 69,973 | Community | Purchased surface water |
| 9 | City of Palo Alto | Santa Clara | 67,231 | Community | Purchased surface water |
| 10 | City of Gilroy | Santa Clara | 59,203 | Community | Groundwater |
| 11 | City of Morgan Hill | Santa Clara | 47,374 | Community | Groundwater |
| 12 | City of San Jose - Nsj/Alviso | Santa Clara | 45,559 | Community | Purchased surface water |
| 13 | Stanford University | Santa Clara | 35,853 | Community | Purchased surface water |
| 14 | City of Cupertino | Santa Clara | 16,336 | Community | Purchased surface water |
| 15 | Nasa Ames Research Center | Santa Clara | 16,273 | Community | Purchased surface water |
| 16 | Purissima Hills Water District | Santa Clara | 6,245 | Community | Purchased surface water |
| 17 | Santa Clara Valley Medical Center | Santa Clara | 3,000 | Non-transient non-community | Purchased surface water |
| 18 | El Camino Hospital | Santa Clara | 3,000 | Non-transient non-community | Purchased surface water |
| 19 | O'Connor Hospital | Santa Clara | 2,500 | Non-transient non-community | Purchased surface water |
| 20 | Western Digital Technologies, Inc.. | Santa Clara | 2,439 | Non-transient non-community | Groundwater |
| 21 | Csp Henry W. Coe State Park | Santa Clara | 1,205 | Transient non-community | Groundwater |
| 22 | Cal Am - West San Martin | Santa Clara | 1,173 | Community | Groundwater |
| 23 | Gavilan Joint Community College District | Santa Clara | 989 | Non-transient non-community | Groundwater |
| 24 | Christopher Ranch L.L.C. | Santa Clara | 735 | Non-transient non-community | Groundwater |
| 25 | San Martin County Water District | Santa Clara | 627 | Community | Groundwater |
| 26 | Mt. Madonna County Park | Santa Clara | 621 | Transient non-community | Groundwater |
| 27 | Loma Prieta Jusd-Loma Prieta School | Santa Clara | 542 | Non-transient non-community | Groundwater |
| 28 | Gilroy Usd-Rucker School | Santa Clara | 536 | Non-transient non-community | Groundwater |
| 29 | Uvas Canyon County Park | Santa Clara | 509 | Transient non-community | Groundwater |
| 30 | Coyote Valley Rv Resort | Santa Clara | 500 | Community | Groundwater |
| 31 | Cinnabar Hills Golf Club | Santa Clara | 450 | Non-transient non-community | Purchased surface water |
| 32 | Camp Saratoga | Santa Clara | 450 | Community | Surface water |
| 33 | Sanborn-Skyline County Park | Santa Clara | 414 | Transient non-community | Groundwater |
| 34 | Thousand Trails - Morgan Hill | Santa Clara | 413 | Community | Groundwater |
| 35 | Monterey Mushrooms | Santa Clara | 361 | Non-transient non-community | Groundwater |
| 36 | Chemeketa Park Mutual Water Company | Santa Clara | 346 | Community | Surface water |
| 37 | Aldercroft Heights County Water District | Santa Clara | 338 | Community | Surface water |
| 38 | Joseph Grant County Park | Santa Clara | 322 | Transient non-community | Groundwater |
| 39 | Twin Valley Inc. | Santa Clara | 317 | Community | Groundwater |
| 40 | New Avenue Mutual Water Company | Santa Clara | 305 | Community | Groundwater |
| 41 | Mt. Pleasant Water Users Association | Santa Clara | 300 | Community | Purchased surface water |
| 42 | Lupin Lodge | Santa Clara | 300 | Community | Surface water |
| 43 | Lick Observatory-Ucsc | Santa Clara | 284 | Community | Surface water |
| 44 | Walden West | Santa Clara | 273 | Transient non-community | Groundwater |
| 45 | Willow Heights Mansion | Santa Clara | 269 | Transient non-community | Groundwater |
| 46 | Nestldown Ranch | Santa Clara | 265 | Transient non-community | Groundwater |
| 47 | Saratoga Heights Mutual Water Company | Santa Clara | 258 | Community | Purchased surface water |
| 48 | Parkway Lakes Rv Park | Santa Clara | 250 | Community | Groundwater |
| 49 | Casa De Fruta Water System | Santa Clara | 250 | Community | Groundwater |
| 50 | George Chiala Farms Inc. | Santa Clara | 250 | Non-transient non-community | Groundwater |
All other water systems in Santa Clara County (70)
The remaining active systems filed under Santa Clara County, largest first, with the population each reports serving.
- Happy Acres Mwc220
- Coyote Lake County Park216
- Calero County Park210
- Metcalf Motorcycle County Park210
- Mt. Hamilton Grandview Restaurant181
- Saratoga Springs, Inc..180
- Melody Woods Water Company168
- Mt. Eden Mutual Water Company165
- Pacific Point Christian School165
- Lake Canyon Mutual Water Company156
- Chitactac-Adams County Park152
- Roseview Heights Mutual Water Company148
- San Martin Foothills Water Company145
- Raineri Mutual Water Company145
- Kennon Water Company142
- Lakeside Sd-Lakeside School127
- Three Springs Ranch Mutual Water Company110
- Sveadal Water System106
- Oak Dell Park104
- Mecchi Water Company104
- Rancho Robles Mutual Water Company103
- Coyote Creek Golf Club101
- Pg&E Metcalf100
- Z Best Products90
- Green Mountain Water Company80
- Vista Grande Water Users Association79
- Newby Island Landfill, Republic Services77
- Brush and Old Well Mutual Water Company70
- Santa Teresa Meadows Water Company68
- Spring Valley Heights Association Inc.66
- Golden Heights Mutual Water Company66
- Burchell Road Water Association65
- Uvas Pines Rv Park65
- Oakmont Water System61
- Morgan Hill Usd-Machado School60
- Mireval Improvement Association60
- Field Sports Park/Coyote Ranch58
- Los Ranchos De Uvas Water Company58
- Quail Creek Estates Mutual Water Company55
- Sullivan Mutual Water53
- Green Acres Mutual Water53
- Economy Inn52
- Muriel Wright Residential Center52
- Hkn LLC50
- The Rainbow Junction Water System50
- Henry W Coe State Park - Dowdy Ranch50
- Learning Services Corp.48
- South County Retirement Home46
- Aborn Heights Water Mutual Association45
- Valley View Ranches45
- Emerald Valley Mutual Water Company43
- Maria Lane Mutual Water Company42
- Angelo Lane Water Company41
- Mountain Springs Mutual Water Company40
- Chiri Sweet Water Company40
- Stonebridge Mutual Water Co38
- Deer Hill Mutual Water Co36
- Foothill Mutual Water Company36
- Rancho De Lomas Mutual Water Company35
- Lee'S Orchard Owners Association35
- Reforestation Technologies International34
- Vo Uu Buddhist Meditation Association33
- Rockwood Estates Mutual Water Company30
- San Martin Lions Club30
- Live Oak Creek Mutual Water Company30
- Coyote Valley Sporting Clays27
- Rucker Avenue Mutual Water Co25
- Garlic World25
- Fortino Winery25
- Scc Animal Shelter/Airport25
Santa Clara County water systems: frequently asked questions
How many public water systems are in Santa Clara County, California?
EPA's SDWIS records file 121 active public water systems under Santa Clara County, California: 74 community systems (61%), 22 non-transient non-community systems (18%) and 25 transient non-community systems (21%).
Who supplies drinking water in Santa Clara County, CA?
The largest community water systems filed under Santa Clara County are San Jose Water (1,039,920 people served), City of Sunnyvale (157,566 people served) and City of Santa Clara (130,746 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 Santa Clara County's drinking water come from groundwater or surface water?
Of the 121 active public water systems in Santa Clara County, 68% draw mainly on groundwater and 31% on surface water, counting purchased supplies. The largest system, San Jose Water, uses surface water.
Where can I find a water quality report for Santa Clara 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. 74 community systems are filed under Santa Clara 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 Santa Clara 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
- Sacramento County· 164 systems
- Santa Barbara County· 150 systems
- Mendocino County· 144 systems
- El Dorado County· 124 systems
- Merced County· 120 systems
- Tuolumne County· 117 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 Santa Clara County, California”, https://aquacensus.com/water-systems/california/santa-clara (data as of October 1, 2026).