Drinking water quality · 2024

· Verified May 23, 2026

What's in Stockton, CA tap water

32 contaminants were measured in the Stockton, CA water system's 2024 annual report. Each is shown below against its federal limit.

See it on the mapFull source report ↗

Reporting year: 2024
Contaminants measured: 32
Over federal limit: 0
Approaching the limit: 0
Service area: CA
Source: Utility CCR

All within federal limits. Every measured contaminant in this report is below its federal threshold.

PFAS — EPA UCMR5 (2023–2025)

1 PFAS compound above EPA limits in Stockton, CA

About this data

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)

Source:EPA UCMR5· 2023 · 31 samples · 2 detected↗

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

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 Stockton, CA

About this data

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
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
MCAA worst: 2012	0.0125 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.

Metals

Contaminant	Measured	Federal limit	Status
Vanadium	19 ug/LAverageGroundwater	50 ug/LNL	Within the limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avg19 ug/Lrange0–37 ug/L74% of limit SewdPlant 0% of limit
Chromium, HexavalentHexavalent chromium ('chromium-6') — the more toxic form of chromium.	2.5 ug/LAverageGroundwater	10 ug/LMCL	Within the limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avg2.5 ug/Lrange0–8.4 ug/L84% of limit SewdPlant 0% of limit
AluminumA common element sometimes used as a treatment coagulant.	Not detected mg/LAverageGroundwater	1 mg/LMCL	Within the limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avgNot detected mg/Lrange0–0.06 mg/L6% of limit SewdPlant 0% of limit
BoronA naturally occurring element from rock and soil.	Not detected mg/LAverageGroundwater	1 mg/LNL	Within the limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avgNot detected mg/Lrange0–0.14 mg/L14% of limit SewdPlant 0% of limit
Chromium, TotalTotal chromium — the sum of all chromium forms, from natural deposits and industrial discharge.	Not detected ug/LAverageGroundwater	50 ug/LMCL	Within the limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avgNot detected ug/Lrange0–10 ug/L20% of limit SewdPlant 0% of limit
CalciumA naturally occurring mineral that contributes to water hardness.	33 mg/LAverageGroundwater	None set	Detected — no federal limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avg33 mg/Lrange6.1–61 mg/L SewdPlant
MagnesiumA naturally occurring mineral that contributes to water hardness.	16 mg/LAverageGroundwater	None set	Detected — no federal limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avg16 mg/Lrange1.9–34 mg/L SewdPlant
PotassiumA naturally occurring mineral from rock and soil.	4.9 mg/LAverageGroundwater	None set	Detected — no federal limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avg4.9 mg/Lrange0.81–7.2 mg/L SewdPlant
SodiumA naturally occurring salt component.	23 mg/LAverageGroundwater	None set	Detected — no federal limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avg23 mg/Lrange7.3–42 mg/L SewdPlant

Disinfectants

Contaminant	Measured	Federal limit	Status
ChlorineA disinfectant added to drinking water to kill bacteria and viruses.	0.88 mg/LAverageSystem-wide	4 mg/LMRDL	Within the limit

Radionuclides

Contaminant	Measured	Federal limit	Status
Gross AlphaGross alpha particle activity — a combined measure of alpha-emitting radioactive substances.	3.1 pCi/LAverageSystem-wide	15 pCi/LMCL	Within the limit

PFAS ("forever chemicals")

Contaminant	Measured	Federal limit	Status
Perfluorohexanesulfonic acidPerfluorohexanesulfonic acid, a PFAS 'forever chemical.'	0.29 ng/LAverageGroundwater	3 ng/LNL	Within the limit
Perfluoropentanoic acidPerfluoropentanoic acid, a shorter-chain PFAS 'forever chemical.'	0.13 ng/LAverageGroundwater	None set	Detected — no federal limit

Microbial

Contaminant	Measured	Federal limit	Status
Escherichia coli (E. coli)Escherichia coli — bacteria found in the gut of humans and animals.	0MaximumMonthly	0MCL	None detected

VOCs & pesticides

Contaminant	Measured	Federal limit	Status
1,2,3-TCP	Not detected ng/LAverageGroundwater	5 ng/LMCL	Within the limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avgNot detected ng/Lrange0–5 ng/L100% of limit SewdPlant 0% of limit
Dichlorodifluoromethane	Not detected ug/LAverageGroundwater	1000 ug/LNL	Within the limit
TrichloroethyleneAn industrial solvent (TCE) used in metal degreasing.	Not detected ug/LAverageGroundwater	5 ug/LMCL	Within the limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avgNot detected ug/Lrange0–0.56 ug/L11% of limit SewdPlant 0% of limit

Physical & aggregate

Contaminant	Measured	Federal limit	Status
AlkalinityA measure of the water's capacity to neutralize acids.	171 mg/LAverageGroundwater	None set	Detected — no federal limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avg171 mg/Lrange120–270 mg/L SewdPlant
HardnessA measure of dissolved calcium and magnesium minerals.	150 mg/LAverageGroundwater	None set	Detected — no federal limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avg150 mg/Lrange23–290 mg/L SewdPlant
pHA measure of how acidic or basic the water is.	8AverageGroundwater	None set	Detected — no federal limit
+By source (2)— Groundwater, Sewd GroundwaterPlant avg8range5.8–8.9 SewdPlant
TOCTotal organic carbon — a measure of organic material dissolved in the water.	2.2 mg/LMaximumSystem-wide	None set	Detected — no federal limit
TurbidityA measure of cloudiness from suspended particles in the water.	0.08 NTUMaximumSystem-wide	None set	Detected — no federal limit

Source: Stockton, CA's 2024 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.