County · California
Napa County, California: drinking water records
Explore EPA records for 28 community water systems across 10 ZIP codes in Napa 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 5 of the 28 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 28 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 |
|---|---|---|---|---|---|
| American Canyon, City of CA2810005 | 21,437 | 95 | 0 | 9 | 0 ppbbelow the action level |
| Calistoga, City of CA2810002 | 5,610 | 240 | 4 | 8 | 0 ppbbelow the action level |
| St. Helena, City of CA2810004 | 5,386 | 300 | 0 | 10 | 0 ppbbelow the action level |
| Napa, City of CA2810003 | 84,804 | 164 | 0 | 0 | 0 ppbbelow the action level |
| Town of Yountville CA2810007 | 2,787 | 120 | 0 | 0 | 0 ppbbelow the action level |
| Howell Mountain Mutual Water Company CA2810001 | 1,240 | 0 | 0 | 3 | 0 ppbbelow the action level |
| Veterans Home of California CA2810008 | 1,000 | 0 | 0 | 1 | 0 ppbbelow the action level |
| Berryessa Highlands CA2810013 | 715 | 0 | 0 | 15 | 0 ppbbelow the action level |
| Berryessa Estates (Lbrid) CA2800526 | 474 | 0 | 0 | 4 | 0 ppbbelow the action level |
| Berryessa Pines Water System CA2810009 | 261 | 0 | 0 | 1 | 0 ppbbelow the action level |
| Hess Winery CA2801016 | 250 | 0 | 0 | 1 | 7 ppbbelow the action level |
| Meyers Water Co. CA2800530 | 250 | 0 | 0 | 1 | 8.2 ppbbelow the action level |
| Spanish Flat Water District CA2810014 | 230 | 0 | 0 | 1 | 0 ppbbelow the action level |
| Capell Valley Estates CA2800543 | 208 | 0 | 0 | 1 | 3.3 ppbbelow the action level |
| Napa River Ranch CA2800531 | 70 | 0 | 0 | 2 | 4.4 ppbbelow the action level |
| La Tierra Heights Mutual CA2800525 | 67 | 0 | 0 | 1 | 0 ppbbelow the action level |
| Milton Road Water Company CA2801080 | 44 | 0 | 0 | 1 | 0 ppbbelow the action level |
| R Ranch at the Lake CA2800593 | 28 | 0 | 0 | 1 | 0 ppbbelow the action level |
| Pacific Union College CA2810012 | 1,958 | 0 | 0 | 0 | 7 ppbbelow the action level |
| Adventist Health - St. Helena Hospital CA2800625 | 817 | 0 | 0 | 0 | 0 ppbbelow the action level |
| Circle Oaks Water District CA2800521 | 500 | 0 | 0 | 0 | 0 ppbbelow the action level |
| Tucker Acres Mutual Water Co. CA2800516 | 200 | 0 | 0 | 0 | 14 ppbbelow the action level |
| Linda Vista Mutual Water Co CA2800528 | 90 | 0 | 0 | 0 | 0 ppbbelow the action level |
| Mondavi Farm Worker Center CA2800040 | 66 | 0 | 0 | 0 | 0 ppbbelow the action level |
| River Ranch Farm Worker Center CA2800035 | 66 | 0 | 0 | 0 | 0 ppbbelow the action level |
| Calistoga Farm Worker Center CA2800039 | 65 | 0 | 0 | 0 | 0 ppbbelow the action level |
| Linda Falls Terrace Mutual CA2800527 | 35 | 0 | 0 | 0 | 0 ppbbelow the action level |
| Vailima Estates Mutual Water CA2800532 | 25 | 0 | 0 | 0 | 0 ppbbelow the action level |
USGS · Monitoring stations
The water, more recently.
Available station readings in Napa 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 Napa County
10ZIP 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
- American Canyon
- Angwin
- Deer Park
- Napa
- Oakville
- Rutherford
- St. Helena
- Yountville
View ZIP areas and understand coverage
- 94503American Canyon
- 94508Angwin
- 94558Napa
- 94559Napa
- 94562Oakville
- 94567
- 94573Rutherford
- 94574St. Helena
- 94576Deer Park
- 94599Yountville
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.