County · California
Merced County, California: drinking water records
Explore EPA records for 22 community water systems across 19 ZIP codes in Merced County, then find water-testing resources and available recent monitoring-station readings.
Data as of EPA UCMR 5 final release, August 2026 (file dated Aug 28, 2026) · EPA SDWIS 2026Q2 (file dated Jul 9, 2026). How we build these pages
Drinking-water records
EPA survey and compliance records are historical reports. UCMR 5 results are available for 11 of the 22 listed systems in this snapshot. A system with no reported PFAS detection is not a test of every tap or every contaminant.
System population figures are summed from EPA registry records and can overlap where wholesalers and retail systems serve the same people. They are not a Census county-population estimate.
Water systems in this county
All 22 active community systems in the available county records, sorted by record completeness. Scroll the table to explore more systems.
| Water system | People served | PFAS survey results | PFAS found | Health-based violations | Lead, 9 in 10 homes at or below |
|---|---|---|---|---|---|
| City of Los Banos CA2410005 | 47,419 | 780 | 0 | 1 | 0 ppbbelow the action level |
| City of Livingston CA2410004 | 14,894 | 480 | 0 | 2 | 0 ppbbelow the action level |
| Winton Water & Sanitary Dist CA2410010 | 9,745 | 180 | 0 | 1 | 0 ppbbelow the action level |
| City of Dos Palos CA2410002 | 7,452 | 120 | 0 | 27 | 0 ppbbelow the action level |
| City of Gustine CA2410003 | 6,110 | 240 | 0 | 1 | 0 ppbbelow the action level |
| Hilmar County Water District CA2410012 | 5,504 | 60 | 0 | 14 | 0 ppbbelow the action level |
| Planada CSD CA2410007 | 4,164 | 360 | 3 | 1 | 0 ppbbelow the action level |
| City of Merced CA2410009 | 93,692 | 1,260 | 4 | 0 | 0 ppbbelow the action level |
| City of Atwater CA2410001 | 29,479 | 480 | 10 | 0 | 0 ppbbelow the action level |
| Delhi Cwd CA2410006 | 7,784 | 240 | 2 | 0 | 0 ppbbelow the action level |
| Cal Am - Meadowbrook CA2410008 | 5,656 | 180 | 1 | 0 | 6 ppbbelow the action level |
| Le Grand Comm Services Dist CA2410011 | 1,739 | 0 | 0 | 8 | 0 ppbbelow the action level |
| Castle Airport CA2410700 | 1,650 | 0 | 0 | 1 | 6.9 ppbbelow the action level |
| San Luis Hills CA2400209 | 779 | 0 | 0 | 6 | 0 ppbbelow the action level |
| Volta Community Sd CA2400201 | 406 | 0 | 0 | 1 | 0 ppbbelow the action level |
| Black Rascal Water Company CA2400046 | 367 | 0 | 0 | 1 | 0 ppbbelow the action level |
| Ballico CSD CA2400167 | 238 | 0 | 0 | 1 | 7.4 ppbbelow the action level |
| Country Club County WD CA2400128 | 64 | 0 | 0 | 1 | 0 ppbbelow the action level |
| Santa Nella County Water District CA2410018 | 2,211 | 0 | 0 | 0 | 0 ppbbelow the action level |
| John Latoracca Correctional Facility CA2400172 | 800 | 0 | 0 | 0 | 13.9 ppbbelow the action level |
| El Nido Mobile Home Park CA2400053 | 137 | 0 | 0 | 0 | 0 ppbbelow the action level |
| Evergreen Mobile Home Park CA2400084 | 36 | 0 | 0 | 0 | 0 ppbbelow the action level |
USGS · Monitoring stations
The water, more recently.
Available station readings in Merced County, California. Each measurement keeps its time, unit and original source.
These readings describe water at a monitoring station. They do not test your tap, measure PFAS or lead, or determine whether water is safe to drink or swim in.
Recent observations load when this section comes into view.
How these readings update
We check for updates every 10 minutes while this section is visible and show supported observations from the last 48 hours. The time beside a reading is when USGS measured it; the checked time is when our service retrieved the response. We mark a reading more than 6 hours old as older. Provisional observations can change after USGS review. A missing reading does not mean zero or clean water.
Temperature, pH, dissolved oxygen, turbidity, conductivity, streamflow and water level are shown only where a station reports them. Different measurements have different units and sampling intervals. USGS data and documentation.
Your next step
Water testing, reports & local help.
Use these official directories to find your drinking-water agency, a certified laboratory and public water records. We have not yet added an individually reviewed local resource list for this county.
Official national directories
Water testing
Find your state’s private-well program
EPA’s state directory points well owners to local program information. Services and eligibility vary by state and county.
Water testing
Find a certified drinking-water laboratory
Use EPA’s directory to reach your state’s laboratory certification program. EPA does not provide on-request testing of residential drinking water.
Public records
Find your utility’s Consumer Confidence Report
EPA links to community water-system reports and explains how to read them. Look for your actual supplier rather than assuming every address in a county shares one system.
Public records
Explore USGS water observations
Find current and historical observations from USGS monitoring locations, including available stream, lake, and groundwater data. Measurements vary by station and do not replace a test of your household water.
A county overview cannot identify every property’s water provider. If you use a public water system, confirm its name on your bill and request its annual Consumer Confidence Report. Private wells need their own testing; public-system records do not describe a private well.
Understand water testing and laboratory reportsResource descriptions are compiled by Tap Water Lookup. Review dates describe our source check, not a new water sample. How we review sources · Suggest a correction
Explore your area
Local coverage in Merced County
19ZIP areas in this overview
Explore the water-system records, recent station readings and testing resources on this county page. They describe the systems and stations identified in each section; they are not a separate water test for every community.
Towns and communities
- Atwater
- Ballico
- Cressey
- Delhi
- Dos Palos Y
- El Nido
- Hilmar-Irwin
- Lake Don Pedro
- Le Grand
- Livingston
- Los Banos
- Merced
- Planada
- Santa Nella
- South Dos Palos
- Stevinson
- Winton
View ZIP areas and understand coverage
- 93620Dos Palos Y
- 93635Los Banos
- 93665South Dos Palos
- 95301Atwater
- 95303Ballico
- 95312Cressey
- 95315Delhi
- 95317El Nido
- 95322Santa Nella
- 95324Hilmar-Irwin
- 95333Le Grand
- 95334Livingston
- 95340Merced
- 95341Merced
- 95348Merced
- 95365Planada
- 95369Lake Don Pedro
- 95374Stevinson
- 95388Winton
These Census ZIP Code Tabulation Areas are grouped here by their largest county overlap. A ZIP area can cross county lines and contain several water suppliers or private wells. Place labels reflect Census geography, not verified postal city names or utility service boundaries.
Records for these areas are currently presented in this county overview rather than individual ZIP reports. An unpublished report does not mean there are no water records. Confirm your supplier on your water bill; if you use a private well, testing your own well is the relevant next step.
Sources and scope
EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Database prepared 2026-09-03.
Counts cover the systems that report this county to EPA. A water system may cross county lines. "Found" means at least one result at or above the laboratory reporting level; it is not a compliance finding.
Compiled by Tap Water Lookup from the sources identified on this page. Read the methodology and review process.