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Merced County, California — public water systems

At a glance

120 active public water systems are filed under Merced County, California in EPA's SDWIS records, together reporting 267,324 people served. The largest is City of Merced, which reports serving 93,692 people. 22 are community water systems serving people where they live; the other 98 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

120

Population served

267.3K

Community systems

22

Groundwater share

90.8%

How does Merced County compare with other California counties?

Merced County has the 21st-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 267,324 people served in total, the 27th-largest county figure in the state and 0.6% of the statewide total. The average system here reports serving 2,228 people, about 61% 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 Merced County's drinking water come from?

By primary water source, Merced County's active systems draw on groundwater (109, 91%), surface water (10, 8.3%) and purchased surface water (1, 0.8%). Overall, 91% rely mainly on groundwater (including purchased groundwater) and 9.2% 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 Merced, draws primarily on groundwater.

What kinds of water systems operate in Merced County?

Merced County's active systems break down as 22 community systems (18%), 56 non-transient non-community systems (47%) and 42 transient non-community systems (35%). 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 (67%), local government (25%), state government (6.7%) and federal government (1.7%).

The 50 largest water systems in Merced County

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Active public water systems in Merced County, California
#Water systemCountyPopulation servedTypeSource
1City of MercedMerced93,692CommunityGroundwater
2City of Los BanosMerced47,419CommunityGroundwater
3City of AtwaterMerced29,479CommunityGroundwater
4City of LivingstonMerced14,894CommunityGroundwater
5Winton Water & Sanitary DistMerced9,745CommunityGroundwater
6Delhi CwdMerced7,784CommunityGroundwater
7City of Dos PalosMerced7,452CommunitySurface water
8Cal Trans Erreca Rest AreaMerced6,150Transient non-communitySurface water
9City of GustineMerced6,110CommunityGroundwater
10Cal Am - MeadowbrookMerced5,656CommunityGroundwater
11Hilmar County Water DistrictMerced5,504CommunityGroundwater
12Planada CsdMerced4,164CommunityGroundwater
13Santa Nella County Water DistrictMerced2,211CommunitySurface water
14Le Grand Comm Services DistMerced1,739CommunityGroundwater
15Castle AirportMerced1,650CommunityGroundwater
16Hilmar Cheese CompanyMerced1,629Non-transient non-communityGroundwater
17Dole Atwater PlantMerced1,500Non-transient non-communityGroundwater
18Lake Yosemite County ParkMerced1,200Transient non-communityGroundwater
19Mcswain Elementary SchoolMerced1,046Non-transient non-communityGroundwater
20Liberty Packing Company LLCMerced1,020Non-transient non-communityGroundwater
21John Latoracca Correctional FacilityMerced800CommunityGroundwater
22San Luis HillsMerced779CommunitySurface water
23Cdpr Four Rivers District-San Luis CreekMerced653Transient non-communitySurface water
24The Morning Star Packing CompanyMerced650Non-transient non-communityGroundwater
25Ingomar PackingMerced600Non-transient non-communityGroundwater
26Planada ElementaryschoolMerced567Non-transient non-communityGroundwater
27Delhi Kingdom HallMerced452Transient non-communityGroundwater
28Joseph Gallo Cheese Co.Merced407Non-transient non-communityGroundwater
29Volta Community SdMerced406CommunityGroundwater
30Sensient Natural Ingredients LLCMerced400Non-transient non-communityGroundwater
31Black Rascal Water CompanyMerced367CommunityGroundwater
32Cdpr Four Rivers District-BasaltMerced363Transient non-communitySurface water
33Cdpr-HatfieldMerced352Transient non-communityGroundwater
34Turlock Golf & Country ClubMerced350Non-transient non-communityGroundwater
35Washington SchoolMerced338Non-transient non-communityGroundwater
36Charleston SchoolMerced325Non-transient non-communityGroundwater
37Saputo Dairy Foods USA, LLCMerced320Non-transient non-communityGroundwater
38LDS Church AtwaterMerced300Transient non-communityGroundwater
39Schelby SchoolMerced290Non-transient non-communityGroundwater
40Cdpr-McconnellMerced286Transient non-communityGroundwater
41Merquin Elementary SchoolMerced284Non-transient non-communityGroundwater
42Hagaman County ParkMerced280Transient non-communityGroundwater
43LDS Church MercedMerced257Transient non-communityGroundwater
44Yosemite WholesaleMerced250Non-transient non-communityGroundwater
45Firebaugh Travel Plaza (Sw)Merced250Transient non-communitySurface water
46E & J Gallo WineryMerced245Non-transient non-communityGroundwater
47Foster Farms Delhi Feedmill Collier RoadMerced244Non-transient non-communityGroundwater
48Ballico CsdMerced238CommunityGroundwater
49Henderson County ParkMerced230Transient non-communityGroundwater
50Classic Yam Water SystemMerced224Non-transient non-communityGroundwater

All other water systems in Merced County (70)

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

Merced County water systems: frequently asked questions

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

EPA's SDWIS records file 120 active public water systems under Merced County, California: 22 community systems (18%), 56 non-transient non-community systems (47%) and 42 transient non-community systems (35%).

Who supplies drinking water in Merced County, CA?

The largest community water systems filed under Merced County are City of Merced (93,692 people served), City of Los Banos (47,419 people served) and City of Atwater (29,479 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 Merced County's drinking water come from groundwater or surface water?

Of the 120 active public water systems in Merced County, 91% draw mainly on groundwater and 9.2% on surface water, counting purchased supplies. The largest system, City of Merced, uses groundwater.

Where can I find a water quality report for Merced 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. 22 community systems are filed under Merced 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 Merced 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 Merced County, California”, https://aquacensus.com/water-systems/california/merced (data as of October 1, 2026).