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Monterey County, California — public water systems

At a glance

307 active public water systems are filed under Monterey County, California in EPA's SDWIS records, together reporting 476,419 people served. The largest is Cwsc Salinas, which reports serving 123,679 people. 155 are community water systems serving people where they live; the other 152 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

307

Population served

476.4K

Community systems

155

Groundwater share

96.1%

How does Monterey County compare with other California counties?

Monterey County has the 4th-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 476,419 people served in total, the 19th-largest county figure in the state and 1.1% of the statewide total. The average system here reports serving 1,552 people, well below 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 Monterey County's drinking water come from?

By primary water source, Monterey County's active systems draw on groundwater (271, 88%), groundwater under influence of surface water (21, 6.8%), surface water (12, 3.9%) and purchased groundwater (3, 1%). Overall, 96% rely mainly on groundwater (including purchased groundwater) and 3.9% 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, Cwsc Salinas, draws primarily on groundwater.

What kinds of water systems operate in Monterey County?

Monterey County's active systems break down as 155 community systems (50%), 87 non-transient non-community systems (28%) and 65 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 (87%), local government (9.1%), state government (3.3%) and federal government (1%).

The 50 largest water systems in Monterey County

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Active public water systems in Monterey County, California
#Water systemCountyPopulation servedTypeSource
1Cwsc SalinasMonterey123,679CommunityGroundwater
2Cal Am Water Company - MontereyMonterey92,450CommunityGroundwater under influence of surface water
3Alco Water ServiceMonterey56,253CommunityGroundwater
4Marina Coast Water DistrictMonterey38,377CommunityGroundwater
5Soledad, City ofMonterey19,455CommunityGroundwater
6Greenfield, City ofMonterey18,967CommunityGroundwater
7Cwsc King CityMonterey16,334CommunityGroundwater
8Gonzales, City ofMonterey8,327CommunityGroundwater
9Castroville Community Services DistrictMonterey7,515CommunityGroundwater
10Psmcsd - PajaroMonterey6,500CommunityGroundwater
11Soledad Mission WsMonterey6,000Transient non-communityGroundwater
12Cwsc Salinas HillsMonterey5,293CommunityGroundwater
13Correctional Training Facility - SoledadMonterey4,269CommunityGroundwater
14Cwsc Oak HillsMonterey3,161CommunityGroundwater
15Salinas Valley State PrisonMonterey2,930CommunityGroundwater
16Seaside Municipal Water SystemMonterey2,800CommunityGroundwater
17Fort Hunter LiggettMonterey2,753CommunityGroundwater
18Caltrans Camp Roberts Rsra SbMonterey2,560Transient non-communityGroundwater
19Little Bear Water CompanyMonterey2,327CommunityGroundwater
20Cwsc Las LomasMonterey2,084CommunityGroundwater
21Prunetree Shopping Center WsMonterey2,000Non-transient non-communityGroundwater
22Tasco Spreckels Water CompanyMonterey1,772CommunityGroundwater
23Caltrans Camp Roberts Rsra NbMonterey1,750Transient non-communityGroundwater
24Prunedale Shopping Center WsMonterey1,650Non-transient non-communityGroundwater
25Laguna Seca Recreation WsMonterey1,248Non-transient non-communityGroundwater
26Cal Am Water Company - ChualarMonterey1,139CommunityGroundwater
27Cal Am Water Company - Hidden HillsMonterey1,106CommunityGroundwater
28Cal Am Water Company - ToroMonterey1,065CommunityGroundwater
29Csp-Andrew Molera State ReserveMonterey1,005Transient non-communityGroundwater under influence of surface water
30San Antonio Lake Park North WsMonterey1,002Transient non-communityGroundwater
31Cal Am Water Company - Ambler ParkMonterey980CommunityGroundwater
32Santa Lucia Preserve WsMonterey966CommunityGroundwater
33Psmcsd - NormcoMonterey928CommunityGroundwater
34Bud Antle, LLC-Soledad Facility WsMonterey900Non-transient non-communityGroundwater
35Psmcsd - Sunny MesaMonterey880CommunityGroundwater
36Csp-J.P. Burns ParkMonterey802Transient non-communityGroundwater
37Corral De Tierra Country Club WsMonterey705Non-transient non-communityGroundwater
38Elkhorn School WsMonterey694Non-transient non-communityGroundwater
39El Camino Real Ws #16Monterey679Transient non-communityGroundwater
40Prunedale School WsMonterey655Non-transient non-communityGroundwater
41San Antonio Lake Park South WsMonterey653Transient non-communitySurface water
42Cdfw Elkhorn Slough Ecological ReserveMonterey650Transient non-communityGroundwater
43Nepenthe WsMonterey618CommunitySurface water
44Csp-Pfeiffer Big SurMonterey585CommunityGroundwater
45Carmel Riviera MwcMonterey584CommunitySurface water
46Echo Valley School WsMonterey579Non-transient non-communityGroundwater
47San Ardo WdMonterey575CommunityGroundwater
48Monterey Mushrooms - Maher CrtMonterey554Non-transient non-communityGroundwater
49Gabilan WcMonterey535CommunityGroundwater
50Psmcsd - Moss Landing Harbor WsMonterey520CommunityGroundwater

All other water systems in Monterey County (257)

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

Monterey County water systems: frequently asked questions

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

EPA's SDWIS records file 307 active public water systems under Monterey County, California: 155 community systems (50%), 87 non-transient non-community systems (28%) and 65 transient non-community systems (21%).

Who supplies drinking water in Monterey County, CA?

The largest community water systems filed under Monterey County are Cwsc Salinas (123,679 people served), Cal Am Water Company - Monterey (92,450 people served) and Alco Water Service (56,253 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 Monterey County's drinking water come from groundwater or surface water?

Of the 307 active public water systems in Monterey County, 96% draw mainly on groundwater and 3.9% on surface water, counting purchased supplies. The largest system, Cwsc Salinas, uses groundwater.

Where can I find a water quality report for Monterey 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. 155 community systems are filed under Monterey 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 Monterey 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 Monterey County, California”, https://aquacensus.com/water-systems/california/monterey (data as of October 1, 2026).