Tap Water Quality Report
Tap water quality in Stockton, California
Tap water in Stockton, California receives a grade of F (43/100) from TapWaterSafety.org. It's served by CITY OF STOCKTON. The most significant water quality concerns are: PFAS contamination; Arsenic significantly above health guideline; Haloacetic acids (HAA9) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in Stockton's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utility serving Stockton.
PFAS contamination
Severe concernPerfluorooctane sulfonate (PFOS) detected. PFAS are persistent chemicals linked to cancer and immune effects with no known safe exposure threshold.
Arsenic significantly above health guideline
Moderate concernArsenic detected at 2.92 ppb, 730x above the EWG health guideline of 0.004 ppb.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 27.8 ppb, 463x above the EWG health guideline of 0.06 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 CITY OF STOCKTON (system ID CA3910012) for the last 3 years. Checked 2026-10-07.
| Rule | Type | Since | Status |
|---|---|---|---|
| Nitrate Rule | Missed testing or reporting | 01/01/2024 | Open |
| Lead and Copper Rule | Missed testing or reporting | 10/01/2021 | Open |
| Stage 2 Disinfectants and Disinfection Byproducts Rule | Contaminant above the legal limit | 04/01/2023 | Open |
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 Stockton
Filters matched to the specific contaminants in Stockton's water supply.
Filter certified for PFOA/PFOS (NSF/ANSI 53 or 58)
$180-$750Reverse osmosis and some carbon block filters reduce PFAS. Look for certification to NSF/ANSI 53 or 58 for PFOA/PFOS.
Reverse osmosis certified for arsenic (NSF/ANSI 58)
$429-$599Reverse osmosis certified under NSF/ANSI 58 for arsenic is the most reliable home option.
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 Stockton'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 |
|---|---|---|---|---|---|---|---|---|
| Arsenic Heavy metal |
2.92 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 730× over |
| Haloacetic acids (HAA9) Disinfection byproduct |
27.8 ppb | 0.06 | — | — | — | — | — | 463× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
36.2 ppb | 0.1 | 60.0 | 60 | — | — | — | 362× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
43.4 ppb | 0.15 | 80.0 | 100 | — | — | — | 290× over |
| Chromium (hexavalent) Heavy metal |
2.71 ppb | 0.02 | — | — | — | — | — | 136× over |
| Bromodichloromethane Disinfection byproduct |
6.27 ppb | 0.06 | — | — | — | — | — | 105× over |
| Trichloroacetic acid Disinfection byproduct |
9.35 ppb | 0.1 | — | — | — | — | — | 94× over |
| Chloroform Disinfection byproduct |
31.7 ppb | 0.4 | — | — | — | — | — | 79× over |
| Dichloroacetic acid Disinfection byproduct |
14.6 ppb | 0.2 | — | — | — | — | — | 73× over |
| Dibromoacetic acid Disinfection byproduct |
1.71 ppb | 0.03 | — | — | — | — | — | 57× over |
| Dibromochloromethane Disinfection byproduct |
4.18 ppb | 0.1 | — | — | — | — | — | 42× over |
| Nitrate Inorganic |
2.73 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 20× over |
| Uranium Radiological |
4.47 pCi/L | 0.43 | 20.0 | 30 | 30 | 0.43 | — | 10× over |
| Bromoform Disinfection byproduct |
2.97 ppb | 0.5 | — | — | — | — | — | 5.9× over |
| Perfluorooctane sulfonate (PFOS) PFAS |
0.804 ppt | 0.3 | 4.0 | 100 | 100 | 1 | — | 2.7× over |
| Radium, combined (-226 and -228) Radiological |
0.05 pCi/L | 0.05 | 5.0 | — | — | — | — | Below guideline |
| Vanadium Other |
16.7 ppb | 21.0 | — | — | — | — | — | Below guideline |
| 1,2,3-Trichloropropane Other |
0.000518 ppb | 0.0007 | — | — | — | — | — | Below guideline |
| Chlorate Disinfection byproduct |
56.4 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Barium Heavy metal |
112.6 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Manganese Heavy metal |
5.67 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| 1,4-Dioxane Semi-volatile organic compound |
0.00744 ppb | 0.35 | — | — | 50 | 1 | — | Below guideline |
| Monobromoacetic acid Disinfection byproduct |
0.19 ppb | 25.0 | — | — | — | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
0.296 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Molybdenum Other |
0.211 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.387 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| 1,1-Dichloroethane Volatile organic compound |
0.000413 ppb | 3.0 | — | — | — | — | — | Below guideline |
| Chromium (total) Heavy metal |
0.545 ppb | — | 100.0 | — | — | — | — | 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 CITY OF STOCKTON.