Water Quality Report · Updated October 07, 2026
CITY OF STOCKTON
CITY OF STOCKTON delivers tap water graded F (43/100) by TapWaterSafety.org. The utility serves approximately 191,302 residents in STOCKTON, California using surface water. 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. For questions, the utility can be reached at 209-937-8438.
Is STOCKTON tap water safe to drink?
CITY OF STOCKTON delivers tap water that earns a grade of F (43/100) from TapWaterSafety.org — a poor rating, with significant contamination concerns and/or recent violations.
The utility serves 191,302 residents in STOCKTON, drawing from surface water.
Public testing data identifies 15 contaminants in this water above EWG's health-based guidelines, including: Arsenic, Haloacetic acids (HAA9), Haloacetic acids (HAA5), Total trihalomethanes (TTHMs), Chromium (hexavalent), Bromodichloromethane, Trichloroacetic acid, Chloroform, Dichloroacetic acid, Dibromoacetic acid, Dibromochloromethane, Nitrate, Uranium, Bromoform, Perfluorooctane sulfonate (PFOS). For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
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.
Quick actions for STOCKTON residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for CITY OF 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.
Contact CITY OF STOCKTON
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Treatment Plant
Recommended water filters for STOCKTON
Filters matched to the specific contaminants in this 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.
Score breakdown
This utility's overall score of 43/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). 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 (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
CITY OF STOCKTON service area
This water system serves 1 community in San Joaquin County, California. Click any city for its dedicated tap water quality page.
Find the right filter for STOCKTON water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.