Drinking water quality · 2025
· Verified
What's in City of Stockton, CA tap water
121 contaminants were measured in the City of Stockton, CA water system's 2025 annual report. Each is shown below against its federal limit — 1 sit at or above that limit.
- Reporting year
- 2025
- Contaminants measured
- 121
- Over federal limit
- 1
- Approaching the limit
- 1
- Worst contaminant
- Odor
- Service area
- CA
1.6× the limit
state-level CCR
At or above the federal limit
Approaching the limit (≥ 80%)
PFAS — EPA UCMR5 (2023–2025)
1 PFAS compound above EPA limits in City of Stockton, CA
The EPA finalized the first-ever federal drinking-water limits for six PFAS compounds in April 2024. These numbers come straight from EPA's UCMR5 lab dataset — every U.S. system serving more than 3,300 people tested every PFAS sample at an entry point to its distribution system. PFAS not listed below were either tested and not detected, or not yet sampled.
PFOS (Perfluorooctane sulfonic acid)
● Over EPA limit (1.2×)Measured 4.8 ng/LEPA limit 4 ng/LSample year 2023Samples 2 detect / 31
below national p90 (19.900000000000006 ng/L across detecting U.S. systems)
PWSID CA3910012 · Source: EPA UCMR5. Limits per EPA's April 2024 PFAS National Primary Drinking Water Regulation. PFAS values reported in nanograms per liter (ng/L) — note that 1 ng/L = 1 part per trillion.
Where your water comes from · EPA SDWIS
City of Stockton, CA's drinking water comes from ground water, drawn from 18 sources.
Source
18ground water
- WELL NO. · 9
- WELL NO. 03 SSS
- WELL NO. 15 - STANDBY
- DWSP-DELTA WATER SOURCE-RAW
- + 6 more
Treatment
17treatment plants
- WELL NO. 15 - TREATED - XCLD - STDBY
- WELL NO. 10R - TREATED - XCLD
- WELL NO. 27 - TREATED - XCLD
- + 14 more
Distribution
0storage units
Also buys water from STOCKTON EAST WATER DISTRICT.
Source: EPA SDWIS facilities inventory. Methodology.
Historical readings · EPA Six-Year Review (2012–2019)
4 contaminants historically over EPA limits in City of Stockton, CA
Every U.S. public water system reports compliance-monitoring data to EPA. The Six-Year Review releases the 2012–2019 window as a single dataset — here's what your system reported, year by year. Values shown are the highest detection per analyte per year, compared to the federal MCL.
| Contaminant | Worst detection | EPA limit | Years (2012–2019) |
|---|---|---|---|
NITRATE NITRITE worst: 2012 | 500 mg/L 50.0× | 10 mg/L | '12'15'16'17'18 |
BROMATE worst: 2014 | 0.036 mg/L 3.6× | 0.01 mg/L | '12'13'14'15'16'18'19 |
TTHM worst: 2015 | 0.14 mg/L 1.8× | 0.08 mg/L | '12'13'14'15'16'17'18'19 |
HAA5 worst: 2013 | 0.0963 mg/L 1.6× | 0.06 mg/L | '12'13'14'15'16'17'18'19 |
ARSENIC worst: 2013 | 0.009 mg/L 90% near national p90 | 0.01 mg/L | '12'13'14'15'16'17'18'19 |
NITRATE worst: 2012 | 7.01 mg/L within | 10 mg/L | '12'13'14'15'16'17'18'19 |
GROSS BETA worst: 2012 | 1.44 mrem/yr within | 4 mrem/yr | '12 |
BARIUM worst: 2013 | 0.4 mg/L within above national p90 | 2 mg/L | '12'13'14'15'16'17'18'19 |
TCE worst: 2013 | 0.00061 mg/L within | 0.005 mg/L | '13 |
CHROMIUM worst: 2018 | 0.012 mg/L within above national p90 | 0.1 mg/L | '17'18 |
SELENIUM worst: 2013 | 0.0059 mg/L within | 0.05 mg/L | '13 |
DBCP worst: 2017 | 0.00001 mg/L within below national p90 | 0.0002 mg/L | '17 |
FLUORIDE worst: 2016 | 0.2 mg/L within | 4 mg/L | '12'13'16'18 |
URANIUM worst: 2013 | 0.0192 ug/L within near national p90 | 30 ug/L | '12'13'14'15'16'17'19 |
MCAA worst: 2012 | 0.0125 mg/L | — | '12'13'14'15'16'17'18'19 |
TCAA worst: 2012 | 0.0216 mg/L | — | '12'13'14'15'16'17'18'19 |
MBAA worst: 2013 | 0.0014 mg/L | — | '13'14'15'16'17'18'19 |
COPPER worst: 2013 | 0.56 mg/L near national p90 | — | '13'19 |
LEAD worst: 2012 | 0.003 mg/L | — | '12'13'14'19 |
DBAA worst: 2012 | 0.0058 mg/L | — | '12'13'14'15'16'17'18'19 |
DCAA worst: 2012 | 0.022 mg/L | — | '12'13'14'15'16'17'18'19 |
BROMODICHLOROMETHANE worst: 2012 | 0.026 mg/L | — | '12'13'14'15'16'17'18'19 |
BROMOFORM worst: 2012 | 0.0092 mg/L | — | '12'13'14'15'16'17'18'19 |
CHLOROFORM worst: 2012 | 0.099 mg/L | — | '12'13'14'15'16'17'18'19 |
DIBROMOCHLOROMETHANE worst: 2012 | 0.02 mg/L | — | '12'13'14'15'16'17'18'19 |
PWSID CA3910012 · Source: EPA Six-Year Review 4 (2012–2019). Values are the highest detection in each calendar year; non-detect years are omitted. Year tags above show every year with a detection.
Physical & aggregate
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| OdorA measure of detectable smell in the water. | 4.835 TONAverageSource water | 3 TONMCL | At or above the limit |
| ColorA measure of visible tint in the water. | 13.25 UNITSAverageSource water | 15 UNITSMCL | Approaching the limit |
| TurbidityA measure of cloudiness from suspended particles in the water. | 2.1285714285714286 NTUAverageSource water | 5 NTUMCL | Within the limit |
| Total Dissolved SolidsTotal dissolved solids — the combined content of all dissolved minerals and salts. | 347.14285714285717 MG/LAverageDistribution | 1000 MG/LMCL | Within the limit |
| Specific ConductanceA measure of how well water conducts electricity, which tracks dissolved mineral content. | 195.75 UMHO/CMAverageSource water | 1600 UMHO/CMMCL | Within the limit |
| AlkalinityA measure of the water's capacity to neutralize acids. | 136.21428571428572 MG/LAverageDistribution | None set | Detected — no federal limit |
| HardnessA measure of dissolved calcium and magnesium minerals. | 82.42857142857143 MG/LAverageSource water | None set | Detected — no federal limit |
| pHA measure of how acidic or basic the water is. | 8.086666666666666 PHAverageEntry point | None set | Detected — no federal limit |
VOCs & pesticides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| 1,2,3-TCP | 0.0032 UG/LAverageSource water | 0.005 UG/LMCL | Within the limit |
| AtrazineA widely used agricultural herbicide that reaches water through runoff. | Not detected UG/LHighest single sampleSource water | 1 UG/LMCL | None detected |
| Benzene | Not detected UG/LHighest single sampleSource water | 1 UG/LMCL | None detected |
| Benzo(a)pyrene | Not detected UG/LHighest single sampleSource water | 0.2 UG/LMCL | None detected |
| Dalapon | Not detected UG/LHighest single sampleSource water | 200 UG/LMCL | None detected |
| Dichloromethane | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Ethylbenzene | Not detected UG/LHighest single sampleSource water | 300 UG/LMCL | None detected |
| Simazine | Not detected UG/LHighest single sampleSource water | 4 UG/LMCL | None detected |
| Toluene | Not detected UG/LHighest single sampleEntry point | 150 UG/LMCL | None detected |
| XylenesA group of industrial solvents found in gasoline and paint. | Not detected UG/LHighest single sampleSource water | 1750 UG/LMCL | None detected |
Radionuclides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Gross AlphaGross alpha particle activity — a combined measure of alpha-emitting radioactive substances. | 7.9775 PCI/LAverageSource water | 15 PCI/LMCL | Within the limit |
| Combined RadiumCombined radium-226 and radium-228 — naturally occurring radioactive elements. | 0.08266111111111112 PCI/LAverageSource water | 5 PCI/LMCL | Within the limit |
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| IronA naturally occurring metal common in groundwater. | 137.77777777777777 UG/LAverageSource water | 300 UG/LMCL | Within the limit |
| Chromium, HexavalentHexavalent chromium ('chromium-6') — the more toxic form of chromium. | 2.675764705882353 UG/LAverageSource water | 10 UG/LMCL | Within the limit |
| ManganeseA naturally occurring metal from soil and rock. | 11.428571428571429 UG/LAverageSource water | 50 UG/LMCL | Within the limit |
| AluminumA common element sometimes used as a treatment coagulant. | 95.71428571428571 UG/LAverageSource water | 1000 UG/LMCL | Within the limit |
| Antimony | Not detected UG/LHighest single sampleSource water | 6 UG/LMCL | None detected |
| Beryllium | Not detected UG/LHighest single sampleSource water | 4 UG/LMCL | None detected |
| BoronA naturally occurring element from rock and soil. | Not detected UG/LHighest single sampleEntry point | None set | None detected |
| Cadmium | Not detected UG/LHighest single sampleEntry point | 5 UG/LMCL | None detected |
| MercuryA toxic metal from erosion of natural deposits and industrial runoff. | Not detected UG/LHighest single sampleEntry point | 2 UG/LMCL | None detected |
| NickelA metal from natural deposits and industrial discharge. | Not detected UG/LHighest single sampleEntry point | 100 UG/LMCL | None detected |
| Thallium | Not detected UG/LHighest single sampleEntry point | 2 UG/LMCL | None detected |
| ZincA naturally occurring metal that can also enter water from corroding pipes. | Not detected UG/LHighest single sampleEntry point | 5000 UG/LMCL | None detected |
| CalciumA naturally occurring mineral that contributes to water hardness. | 6.183333333333334 MG/LAverageSource water | None set | Detected — no federal limit |
| MagnesiumA naturally occurring mineral that contributes to water hardness. | 9.342857142857143 MG/LAverageSource water | None set | Detected — no federal limit |
| PotassiumA naturally occurring mineral from rock and soil. | 2.4285714285714284 MG/LAverageSource water | None set | Detected — no federal limit |
| SodiumA naturally occurring salt component. | 15.533333333333333 MG/LAverageEntry point | None set | Detected — no federal limit |
| Vanadium | 7.85 UG/LAverageSource water | None set | Detected — no federal limit |
Inorganic chemicals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| NitriteA compound from fertilizer runoff, sewage, and erosion of natural deposits. | 0.12666666666666668 MG/LAverageEntry point | 1 MG/LMCL | Within the limit |
| ChlorideA naturally occurring salt compound. | 34.57142857142857 MG/LAverageDistribution | 500 MG/LMCL | Within the limit |
| SulfateA naturally occurring mineral from rock and soil. | 24.571428571428573 MG/LAverageDistribution | 500 MG/LMCL | Within the limit |
| BromideA naturally occurring salt found in source water. | 0.053250000000000006 MG/LAverageSource water | None set | Detected — no federal limit |
Disinfection byproducts
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| PerchlorateA chemical used in rocket fuel and fireworks that can also form during disinfection. | Not detected UG/LHighest single sampleSource water | 6 UG/LMCL | None detected |
Other
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Carbofuran | Not detected UG/LHighest single sampleSource water | 18 UG/LMCL | None detected |
| Carbon Tetrachloride | Not detected UG/LHighest single sampleSource water | 0.5 UG/LMCL | None detected |
| Chlordane | Not detected UG/LHighest single sampleSource water | 0.1 UG/LMCL | None detected |
| Chlorobenzene | Not detected UG/LHighest single sampleSource water | 70 UG/LMCL | None detected |
| Cis Dichloroethylene 12 | Not detected UG/LHighest single sampleSource water | 6 UG/LMCL | None detected |
| Deha | Not detected UG/LHighest single sampleSource water | 400 UG/LMCL | None detected |
| Dehp | Not detected UG/LHighest single sampleSource water | 4 UG/LMCL | None detected |
| Dichloroethane 12 | Not detected UG/LHighest single sampleSource water | 0.5 UG/LMCL | None detected |
| Dichloroethylene 11 | Not detected UG/LHighest single sampleSource water | 6 UG/LMCL | None detected |
| Dichloropropane 12 | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Dinoseb | Not detected UG/LHighest single sampleSource water | 7 UG/LMCL | None detected |
| Diquat | Not detected UG/LHighest single sampleSource water | 20 UG/LMCL | None detected |
| Edb | Not detected UG/LHighest single sampleSource water | 0.05 UG/LMCL | None detected |
| Endothall | Not detected UG/LHighest single sampleSource water | 100 UG/LMCL | None detected |
| Endrin | Not detected UG/LHighest single sampleSource water | 2 UG/LMCL | None detected |
| Glyphosate | Not detected UG/LHighest single sampleSource water | 700 UG/LMCL | None detected |
| Heptachlor | Not detected UG/LHighest single sampleSource water | 0.01 UG/LMCL | None detected |
| Heptachlor Epoxide | Not detected UG/LHighest single sampleSource water | 0.01 UG/LMCL | None detected |
| Hexachlorobenzene | Not detected UG/LHighest single sampleSource water | 1 UG/LMCL | None detected |
| Hexachlorocyclopentadiene | Not detected UG/LHighest single sampleSource water | 50 UG/LMCL | None detected |
| Methoxychlor | Not detected UG/LHighest single sampleSource water | 30 UG/LMCL | None detected |
| O Dichlorobenzene | Not detected UG/LHighest single sampleSource water | 600 UG/LMCL | None detected |
| Oxamyl | Not detected UG/LHighest single sampleSource water | 50 UG/LMCL | None detected |
| P Dichlorobenzene | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Pcb Total | Not detected UG/LHighest single sampleSource water | 0.5 UG/LMCL | None detected |
| Pce | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Pentachlorophenol | Not detected UG/LHighest single sampleSource water | 1 UG/LMCL | None detected |
| Picloram | Not detected UG/LHighest single sampleSource water | 500 UG/LMCL | None detected |
| Styrene | Not detected UG/LHighest single sampleSource water | 100 UG/LMCL | None detected |
| Toxaphene | Not detected UG/LHighest single sampleSource water | 3 UG/LMCL | None detected |
| Trans Dichloroethylene 12 | Not detected UG/LHighest single sampleSource water | 10 UG/LMCL | None detected |
| Trichlorobenzene 124 | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Trichloroethane 111 | Not detected UG/LHighest single sampleSource water | 200 UG/LMCL | None detected |
| Trichloroethane 112 | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Twofourd | Not detected UG/LHighest single sampleSource water | 70 UG/LMCL | None detected |
| Vinyl Chloride | Not detected UG/LHighest single sampleSource water | 0.5 UG/LMCL | None detected |
PFAS ("forever chemicals")
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid, a chlorinated PFAS compound. | Not detected NG/LHighest single sampleEntry point | None set | None detected |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)ADONA, a newer-generation PFAS replacement compound. | Not detected NG/LHighest single sampleDistribution | None set | None detected |
| 4:2 Fluorotelomer sulfonic acid (4:2 FTS)4:2 fluorotelomer sulfonic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleDistribution | None set | None detected |
| 6:2 Fluorotelomer sulfonic acid (6:2 FTS)6:2 fluorotelomer sulfonic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleDistribution | None set | None detected |
| 8:2 Fluorotelomer sulfonic acid (8:2 FTS)8:2 fluorotelomer sulfonic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleDistribution | None set | None detected |
| 9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic acid (9Cl-PF3ONS)9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid, a chlorinated PFAS compound. | Not detected NG/LHighest single sampleDistribution | None set | None detected |
| Hexafluoropropylene oxide dimer acidHFPO-DA ('GenX chemicals'), a newer-generation PFAS replacement compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluoro-3-methoxypropanoic acid (PFMPA)Perfluoro-3-methoxypropanoic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleEntry point | None set | None detected |
| Perfluoro-4-methoxybutanoic acid (PFMBA)Perfluoro-4-methoxybutanoic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluoro(2-ethoxyethane)sulfonic acid (PFEESA)Perfluoro(2-ethoxyethane)sulfonic acid, a PFAS-related compound. | Not detected NG/LHighest single sampleEntry point | None set | None detected |
| Perfluorodecanoic acid (PFDA)Perfluorodecanoic acid, a longer-chain PFAS 'forever chemical.' | Not detected NG/LHighest single sampleEntry point | None set | None detected |
| Perfluorododecanoic acid (PFDoA)Perfluorododecanoic acid, a longer-chain PFAS 'forever chemical.' | Not detected NG/LHighest single sampleEntry point | None set | None detected |
| Perfluoroheptanesulfonic acid (PFHpS)Perfluoroheptanesulfonic acid, a PFAS 'forever chemical.' | Not detected NG/LHighest single sampleDistribution | None set | None detected |
| Perfluoroheptanoic acidPerfluoroheptanoic acid, a PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluorohexanoic acidPerfluorohexanoic acid, a shorter-chain PFAS 'forever chemical.' | Not detected NG/LHighest single sampleEntry point | None set | None detected |
| Perfluorononanoic acidPerfluorononanoic acid, a PFAS 'forever chemical.' | Not detected NG/LHighest single sampleSource water | None set | None detected |
| Perfluoropentanesulfonic acid (PFPeS)Perfluoropentanesulfonic acid, a PFAS 'forever chemical.' | Not detected NG/LHighest single sampleDistribution | None set | None detected |
| Perfluoropentanoic acidPerfluoropentanoic acid, a shorter-chain PFAS 'forever chemical.' | Not detected NG/LHighest single sampleEntry point | None set | None detected |
| Perfluoroundecanoic acid (PFUnA)Perfluoroundecanoic acid, a longer-chain PFAS 'forever chemical.' | Not detected NG/LHighest single sampleDistribution | None set | None detected |
| PFBAPerfluorobutanoic acid, a shorter-chain PFAS 'forever chemical.' | 1.8285714285714287 NG/LAverageDistribution | None set | Detected — no federal limit |
Source: City of Stockton, CA's 2025 Consumer Confidence Report — the annual drinking-water report every U.S. utility is required to publish. The numbers on this page are the utility's own. A water-quality report covers an entire service area, not a single address.
People also ask about City of Stockton, CA's water
+Is City of Stockton, CA tap water safe to drink in 2025?
The 2025 Consumer Confidence Report for the City of Stockton, CA water utility lists 1 contaminant at or above the federal limit: Odor. Whether that means the water is "unsafe" depends on which contaminant, how long the exposure, and individual health factors. The table on this page shows the measured value, the federal threshold, and the regulated statistic used for compliance.
+What contaminants are in City of Stockton, CA tap water?
121 contaminants were measured in City of Stockton, CA's 2025 Consumer Confidence Report, spanning other, metals, and pfas ("forever chemicals"). 81 have an enforceable federal limit; the rest are detected but unregulated. Every measured value, in the utility's own units, is on this page.
+Which contaminants exceed federal limits in City of Stockton, CA tap water?
One contaminant in City of Stockton, CA's 2025 report sits at or above the federal limit: Odor (1.6× the limit). The EPA enforces these limits against the regulated reporting statistic — typically a running annual average or 90th percentile — not a one-off sample spike.
+What is the worst contaminant in City of Stockton, CA tap water?
The contaminant with the highest measured value relative to its federal limit in the 2025 report is Odor, at 1.6× the federal threshold. It belongs to the physical & aggregate family of contaminants.
+Are any contaminants in City of Stockton, CA tap water approaching the federal limit?
One contaminant is between 80% and 100% of the federal limit in this report: Color. Approaching means measured but not in violation — a margin that can close quickly if conditions change.
+Where does the data on this page come from?
Every value is transcribed from City of Stockton, CA's 2025 Consumer Confidence Report — the annual drinking-water report every U.S. public water utility is required by federal law to publish. The original source document is archived and viewable on this site. A water-quality report covers an entire service area, not a single address.
+How often is City of Stockton, CA's water quality data updated?
Each U.S. public water utility publishes one Consumer Confidence Report per year, covering the prior calendar year's measurements. This page reflects the 2025 report; a new report will replace it once the utility publishes its next annual update.
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