Tap Water Quality Report
Tap water quality in NAPA, California
Tap water in NAPA, California receives a grade of C (75/100) from TapWaterSafety.org. It's served by NAPA, CITY OF. The most significant water quality concerns are: Haloacetic acids (HAA9) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in NAPA's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utility serving NAPA.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 36.2 ppb, 603x above the EWG health guideline of 0.06 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 57.9 ppb, 386x above the EWG health guideline of 0.15 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 36.2 ppb, 362x above the EWG health guideline of 0.1 ppb.
EPA compliance record
Official U.S. EPA records for NAPA, CITY OF (system ID CA2810003) for the last 3 years. Checked 2026-10-07.
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Recommended filters for NAPA
Filters matched to the specific contaminants in NAPA's water supply.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
All contaminants detected in NAPA's tap water
Every contaminant identified, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal. Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA9) Disinfection byproduct |
36.2 ppb | 0.06 | — | — | — | — | — | 603× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
57.9 ppb | 0.15 | 80.0 | 100 | — | — | — | 386× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
36.2 ppb | 0.1 | 60.0 | 60 | — | — | — | 362× over |
| Bromodichloromethane Disinfection byproduct |
13.9 ppb | 0.06 | — | — | — | — | — | 232× over |
| Trichloroacetic acid Disinfection byproduct |
14.1 ppb | 0.1 | — | — | — | — | — | 141× over |
| Chloroform Disinfection byproduct |
39.8 ppb | 0.4 | — | — | — | — | — | 99× over |
| Dibromochloromethane Disinfection byproduct |
4.29 ppb | 0.1 | — | — | — | — | — | 43× over |
| Dichloroacetic acid Disinfection byproduct |
7.85 ppb | 0.2 | — | — | — | — | — | 39× over |
| Dibromoacetic acid Disinfection byproduct |
0.198 ppb | 0.03 | — | — | — | — | — | 6.6× over |
| Chromium (hexavalent) Heavy metal |
0.0341 ppb | 0.02 | — | — | — | — | — | 1.7× over |
| Chlorate Disinfection byproduct |
91.4 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
14.0 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Bromoform Disinfection byproduct |
0.0554 ppb | 0.5 | — | — | — | — | — | Below guideline |
| Vanadium Other |
1.57 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Aluminum Heavy metal |
24.7 ppb | 600.0 | — | 200 | — | 600 | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
0.205 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Molybdenum Other |
0.0944 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.147 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Lithium Other |
1.46 ppb | — | — | — | — | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines, California OEHHA PHGs, EWG Tap Water Database.
Treatment plant contact info
For service issues, water quality concerns, or to request a Consumer Confidence Report from NAPA, CITY OF.