Water Quality Report · Updated May 12, 2026
Stockton Water Authority
Stockton Water Authority delivers tap water graded C (65/100) by TapWaterSafety.org. The utility serves approximately 312,000 residents in Stockton, California using surface water blended from the Delta/Calaveras River. The most significant water quality concerns are: Lead detected in source water; Haloacetic Acids (HAA5) significantly above health guideline; Chromium-6 detected. For questions, the utility can be reached at (213) 840-8623.
Is Stockton tap water safe to drink?
Stockton Water Authority delivers tap water that earns a grade of C (65/100) from TapWaterSafety.org — an average rating, with several contaminants above health guidelines but generally compliant with US legal limits.
The utility serves 312,000 residents in Stockton, drawing from surface water blended (Delta/Calaveras River) and disinfecting with chloramine.
Public testing data identifies 15 contaminants in this water above EWG's health-based guidelines, including: Haloacetic Acids (HAA5), Haloacetic Acids (HAA5), Haloacetic Acids (HAA5), Total Trihalomethanes (TTHMs), Total Trihalomethanes (TTHMs), Total Trihalomethanes (TTHMs), Nitrate, Nitrate, Chromium-6 (Hexavalent), Chromium-6 (Hexavalent), Chromium-6 (Hexavalent), Nitrate, Lead, Lead, Lead. 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.
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for Stockton Water Authority.
Lead detected in source water
Severe concernLead detected at 1.1 ppb. EWG considers no level of lead safe; EPA's action level is 15 ppb.
Haloacetic Acids (HAA5) significantly above health guideline
Moderate concernHaloacetic Acids (HAA5) detected at 24.2 ppb, 242x above the EWG health guideline of 0.1 ppb.
Chromium-6 detected
Moderate concernChromium-6 detected at 0.24 ppb.
Contact Stockton Water Authority
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Water Quality Contact
For questions about contaminants, test results, or your Consumer Confidence Report.
Treatment Plant
Recommended water filters for Stockton
Filters matched to the specific contaminants in this water supply.
NSF/ANSI 53 certified for lead removal
$80-$750NSF 53 is the gold standard certification for lead removal. Required when lead is a documented concern.
Carbon block (NSF/ANSI 42 + 53)
$40-$750Activated carbon is highly effective for disinfection byproducts like TTHM and HAA5.
Reverse Osmosis
$249-$750Chromium-6 requires reverse osmosis for reliable removal. Standard carbon filters do not address it.
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 65/100 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 |
|---|---|---|---|---|---|---|---|---|
| Haloacetic Acids (HAA5) Disinfection byproduct |
24.2 ppb | 0.1 | 60 | 60 | — | — | 2022 | 242× over |
| Haloacetic Acids (HAA5) Disinfection byproduct |
19.5 ppb | 0.1 | 60 | 60 | — | — | 2024 | 195× over |
| Haloacetic Acids (HAA5) Disinfection byproduct |
19.4 ppb | 0.1 | 60 | 60 | — | — | 2023 | 194× over |
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
56.8 ppb | 0.6 | 80 | 100 | — | — | 2023 | 95× over |
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
52.6 ppb | 0.6 | 80 | 100 | — | — | 2024 | 88× over |
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
45.2 ppb | 0.6 | 80 | 100 | — | — | 2022 | 75× over |
| Nitrate Inorganic |
2.09 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 2022 | 15× over |
| Nitrate Inorganic |
1.8 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 2024 | 13× over |
| Chromium-6 (Hexavalent) Heavy metal |
0.24 ppb | 0.02 | — | — | — | 0.02 | 2024 | 12× over |
| Chromium-6 (Hexavalent) Heavy metal |
0.229 ppb | 0.02 | — | — | — | 0.02 | 2023 | 11× over |
| Chromium-6 (Hexavalent) Heavy metal |
0.208 ppb | 0.02 | — | — | — | 0.02 | 2022 | 10× over |
| Nitrate Inorganic |
1.26 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 2023 | 9.0× over |
| Lead Heavy metal |
1.1 ppb | 0 | 15 | 5 | 10 | 0.2 | 2024 | — |
| Lead Heavy metal |
1.33 ppb | 0 | 15 | 5 | 10 | 0.2 | 2023 | — |
| Lead Heavy metal |
0.83 ppb | 0 | 15 | 5 | 10 | 0.2 | 2022 | — |
| Contaminant | Detected (2024) | EWG | EPA | EU DWD | WHO | CA PHG | Status |
|---|---|---|---|---|---|---|---|
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
52.6 ppb | 0.6 | 80 | 100 | — | — | 88× over |
| Haloacetic Acids (HAA5) Disinfection byproduct |
19.5 ppb | 0.1 | 60 | 60 | — | — | 195× over |
| Lead Heavy metal |
1.1 ppb | 0 | 15 | 5 | 10 | 0.2 | — |
| Chromium-6 (Hexavalent) Heavy metal |
0.24 ppb | 0.02 | — | — | — | 0.02 | 12× over |
| Nitrate Inorganic |
1.8 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 13× over |
| Contaminant | Detected (2023) | EWG | EPA | EU DWD | WHO | CA PHG | Status |
|---|---|---|---|---|---|---|---|
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
56.8 ppb | 0.6 | 80 | 100 | — | — | 95× over |
| Haloacetic Acids (HAA5) Disinfection byproduct |
19.4 ppb | 0.1 | 60 | 60 | — | — | 194× over |
| Lead Heavy metal |
1.33 ppb | 0 | 15 | 5 | 10 | 0.2 | — |
| Chromium-6 (Hexavalent) Heavy metal |
0.229 ppb | 0.02 | — | — | — | 0.02 | 11× over |
| Nitrate Inorganic |
1.26 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 9.0× over |
| Contaminant | Detected (2022) | EWG | EPA | EU DWD | WHO | CA PHG | Status |
|---|---|---|---|---|---|---|---|
| Total Trihalomethanes (TTHMs) Disinfection byproduct |
45.2 ppb | 0.6 | 80 | 100 | — | — | 75× over |
| Haloacetic Acids (HAA5) Disinfection byproduct |
24.2 ppb | 0.1 | 60 | 60 | — | — | 242× over |
| Lead Heavy metal |
0.83 ppb | 0 | 15 | 5 | 10 | 0.2 | — |
| Chromium-6 (Hexavalent) Heavy metal |
0.208 ppb | 0.02 | — | — | — | 0.02 | 10× over |
| Nitrate Inorganic |
2.09 mg/L | 0.14 | 10 | 11.3 | 11.3 | 10 | 15× over |
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, and Stockton Water Authority's Consumer Confidence Report.
Stockton Water Authority 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.