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Is Stockton, CA Tap Water Safe to Drink?

Graded F — but Copper, PFOS and 4 more were detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓

223K residents served 68 water systems PWSID: CA3910012
Overall Score
33.3 / 100
Violations
168 active
Last Updated
May 2026
Source
Surface water
#690 of 694 in California Top 99% nationally
Local Government
High data confidence
Reviewed by WaterVerge Editorial Team · Last updated May 2026
FGRADE
Water Quality Grade
33.3/100
waterverge.com
F 33.3/100

Stockton, CA — Water Quality Report

Stockton's drinking water received a grade of F (33.3 out of 100), indicating failing water quality. The city's 68 water systems serve approximately 223,400 residents using surface water.

Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. UCMR 5 testing detected 6 PFAS compounds, with levels exceeding EPA maximum contaminant levels in the water supply.

The system has 1004 violations on record, including 261 health-based violations. 168 remain unresolved.

Data last updated: May 2026 · Source: EPA SDWIS, UCMR 5
Step 1 See the 13 contaminants we flagged Measured levels for Lead and Copper vs. EPA limits. Step 2 Best filter for pfas Reverse Osmosis or Activated Carbon Block — our tested picks for removing pfas. Step 3 How Stockton compares Stockton scores below nearby cities (avg 57/100).
Analysis

What to know about Stockton's water

Stockton ranks #690 out of 694 cities in California for water quality, placing it among the lowest-rated in the state.

The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection.

Of particular concern: PFAS "forever chemical" levels exceed the 2024 EPA maximum contaminant levels. These synthetic compounds don't break down naturally and require specialized filtration such as reverse osmosis or granular activated carbon.

Hexavalent chromium (chromium-6) was detected at 6.60 µg/L in UCMR 3 testing. While below California's 10 µg/L limit and with no federal MCL set, residents sensitive to this contaminant may consider reverse osmosis filtration.

The system has seen 185 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.

Quality Breakdown

Water quality score

See methodology →
33.3 out of 100 Grade F
A: 90-100
B: 74-89
C: 60-73
F: <50
How is this calculated?
Violations
0/45
F
Historical violation record including health-based and monitoring violations.
Lead & Copper
16/20
B
Lead at 0.0 ppb (90th percentile).
Contaminants
5.3/20
F
6 PFAS compounds detected.
Compliance
8/10
B
Monitoring and reporting compliance with EPA regulations.
Source Risk
4/5
B
Water source: Surface water.
Water Safety

Is Stockton, CA water safe to drink?

Concerns Identified

Stockton's drinking water has significant quality concerns based on EPA testing data. With a grade of F (33.3/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 68 water systems serve approximately 223,400 residents using surface water (rivers, lakes, or reservoirs).

168
Active Violations
0.0 ppb
Lead (90th %ile)
6 compounds
PFAS Detected
10 events
Disaster History

Recent water quality updates for Stockton

A timeline of significant water quality events, violations, and data updates.

PFAS
6 PFAS "forever chemical" compounds detected

PFAS levels exceed EPA maximum contaminant levels. Reverse osmosis or activated carbon filtration recommended.

Update
Water quality data updated

Latest EPA compliance and testing data incorporated into Stockton's water quality assessment. Grade: F (33.3/100).

Violation
4 drinking water violations recorded

3 health-based. Contaminants: Arsenic, Nitrate, Lead and Copper Rule.

Violation
4 drinking water violations recorded

2 health-based. Contaminants: LEAD AND COPPER RULE REVISIONS, Arsenic, Nitrate.

Violation
1 drinking water violation recorded

1 health-based. Contaminants: Revised Total Coliform Rule.

Disaster
SEVERE WINTER STORMS, FLOODING, LANDSLIDES, AND MUDSLIDES

Federal disaster declaration (FEMA DR-3592). Flood event — may have impacted local water infrastructure.

Key contaminant findings

Based on the most recent EPA sampling data for Stockton's water supply.

Lead Within Limits
Detected: 0.0 ppb Limit: 15 ppb (EPA Action Level)

Well within EPA limits.

Copper Exceeds Limit
Detected: 1.50 mg/L Limit: 1.3 mg/L (EPA Action Level)

Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.

PFAS (6 compounds) Exceeds Limit
Detected: Highest: PFOS at 0.0135 µg/L Limit: 0.004 µg/L (EPA MCL)

PFAS "forever chemicals" exceed EPA maximum contaminant levels. Reverse osmosis or granular activated carbon filtration strongly recommended.

Chromium-6 (Hexavalent Chromium) Elevated
Detected: 6.60 µg/L Limit: 10 µg/L (California MCL — no federal limit)

The "Erin Brockovich" chemical. There is no federal MCL, but California has set a limit of 10 µg/L. Reverse osmosis filtration is effective at removing hexavalent chromium.

PFAS "forever chemicals" detected

UCMR 5 testing found 6 PFAS compounds in Stockton's water supply. PFAS are synthetic chemicals that persist indefinitely in the environment and the human body.

Compound Level EPA MCL Status
PFOS 0.0135 µg/L 0.004 µg/L Over MCL
PFBS 0.0085 µg/L 0.004 µg/L Within Limit
PFOA 0.0083 µg/L 0.004 µg/L Over MCL
PFHxS 0.0047 µg/L 0.004 µg/L Within Limit

Violation history

Stockton's water system has 1,004 total violations on record, including 261 health-based violations. 168 remain unresolved. 185 violations were issued in the last 5 years.

MCLMRRPTOtherTTMON
Most recent violations:
Oct 2025 Arsenic Resolved
Oct 2025 Nitrate Resolved
Oct 2025 Lead and Copper Rule Open
Oct 2025 Total Haloacetic Acids (HAA5) Resolved
Jul 2025 LEAD AND COPPER RULE REVISIONS Open

Flood & environmental risk

San Joaquin County has experienced 10 federally declared disasters since 1980. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include San Joaquin R Bl Garwood Bridge A Stockton.

SEVERE WINTER STORMS, FLOODING, LANDSLIDES, AND MUDSLIDES
Flood FEMA DR-3592
SEVERE WINTER STORMS, FLOODING, LANDSLIDES, AND MUDSLIDES
Flood FEMA DR-4683
SEVERE WINTER STORMS, FLOODING, AND MUDSLIDES
Flood FEMA DR-3591

Where does Stockton's water come from?

Stockton's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 68 water systems serving approximately 223,400 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include San Joaquin R Bl Garwood Bridge A Stockton (river).

What Stockton residents can do

Install a water filter

Recommended: Reverse osmosis system. This addresses the specific contaminants found in Stockton's water.

Request your utility's CCR

Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.

Monitor alerts during storms

Stockton's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.

Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.

Contaminant Alerts

Top contaminants to know

View all ↓
Lead (90th percentile)
Inorganic / Heavy Metal
Safe
0.0 ppb
EPA Action Level: 15 ppb · 0% of limit
Safe Level
Copper (90th percentile)
Inorganic
Over Limit
1.50 mg/L
EPA Action Level: 1.3 mg/L · +16% over limit
Exceeds Limit
PFOS
PFAS / Forever Chemical
Over MCL
0.0135 µg/L
EPA MCL: 0.004 µg/L · +20% over limit
Exceeds MCL
HAA5 (Disinfection Byproducts)
Disinfection Byproduct
Safe
21.3 µg/L
EPA MCL: 60 µg/L · 35% of limit
Within LimitUCMR 4 DataHAA6Br: 7.9 µg/LHAA9: 27.8 µg/L
Chromium-6 (Hexavalent Chromium)
Inorganic
Elevated
6.60 µg/L
CA MCL (no federal MCL): 10 µg/L · 66% of limit
DetectedUCMR 3 Data
Strontium
Inorganic
Elevated
790.0 µg/L
EPA Health Ref Level: 1,500 µg/L · 53% of limit
DetectedUCMR 3 Data
1,4-Dioxane
Organic
Elevated
0.21 µg/L
EPA Health Advisory: 0.35 µg/L · 60% of limit
DetectedUCMR 3 Data
Manganese
Inorganic
Over SMCL
77.0 µg/L
EPA Secondary MCL: 50 µg/L · +20% over limit
Over SMCLUCMR 4 Data
NDMA (N-Nitrosodimethylamine)
Disinfection Byproduct
Elevated
5.1 ng/L
CA Public Health Goal: 10 ng/L · 51% of limit
DetectedProbable CarcinogenUCMR 2 Data (2008–2010)
Perchlorate
Inorganic
Over CA MCL
19.00 µg/L
CA MCL (no federal MCL): 6 µg/L · +20% over limit
Over CA MCLUCMR 1 Data (2001–2005)
Vanadium
Inorganic
Over HA
33.00 µg/L
EPA Short-term HA: 21 µg/L · +20% over limit
Over Health AdvisoryUCMR 3 Data
Chlorate
Disinfection Byproduct
Over HA
440.0 µg/L
EPA Lifetime HA: 210 µg/L · +20% over limit
Over Health AdvisoryUCMR 3 Data
Molybdenum
Inorganic
Detected
1.60 µg/L
EPA Lifetime HA: 40 µg/L · 4% of limit
DetectedUCMR 3 Data
PFAS Testing

Forever chemicals overview

National PFAS report →
30
Compounds tested
6
Detected
2
Exceed EPA MCL
5.45
Hazard Index
PFOS max: 0.0135 µg/L PFOA max: 0.0083 µg/L
Compliance Record

Violation summary

1004
Total violations
261
Health-based
168
Active / unresolved
Oct 2025
Most recent violation
Compliance Record

Violations & advisories

1004 Total
168 Active
261 Health-based
836 Resolved
2 SNC
Violations by category
Total Coliform Rule
217
Miscellaneous Other Rules
140
Nitrate Rule
112
Volatile Organic Chemicals
107
Consumer Confidence Rule
90
Oct 2025 Active
Lead and Copper Rule
Monitoring & Reporting
Monitoring & Reporting 0
Jul 2025 Active
LEAD AND COPPER RULE REVISIONS
Reporting
Reporting 0
Jul 2025 Active
LEAD AND COPPER RULE REVISIONS
Reporting
Reporting 0
May 2025 Active
Public Notice
Other Violation 0
Apr 2025 Active
Lead and Copper Rule
Treatment Technique
Health-Based Health 0
Oct 2024 Active
LEAD AND COPPER RULE REVISIONS
Reporting
Reporting 0
Oct 2024 Active
LEAD AND COPPER RULE REVISIONS
Treatment Technique
Health-Based Health 0
Oct 2024 Active
LEAD AND COPPER RULE REVISIONS
Reporting
Reporting 0
Oct 2024 Active
LEAD AND COPPER RULE REVISIONS
Treatment Technique
Health-Based Health 0
Oct 2024 Active
Lead and Copper Rule
Monitoring & Reporting
Monitoring & Reporting 0
Jul 2024 Active
Consumer Confidence Rule
Other Violation 0
Feb 2024 Active
Revised Total Coliform Rule
Reporting
Reporting 0
Oct 2023 Active
Lead and Copper Rule
Monitoring & Reporting
Monitoring & Reporting 0
Oct 2023 Active
Lead and Copper Rule
Monitoring & Reporting
Monitoring & Reporting 0
Jan 2022 Active
Lead and Copper Rule
Monitoring & Reporting
Monitoring & Reporting 0
Oct 2021 Active
Lead and Copper Rule
Monitoring & Reporting
Monitoring & Reporting 0
Jul 2021 Active
Consumer Confidence Rule
Other Violation 0
Jul 2021 Active
Consumer Confidence Rule
Other Violation 0
Oct 2020 Active
Consumer Confidence Rule
Other Violation 0
Oct 2020 Active
Lead and Copper Rule
Monitoring & Reporting
Monitoring & Reporting 0
Showing 20 of 1004 violations
Industrial pollution

Top industrial polluters within 10 miles of Stockton

Industrial polluters nearby

Reported releases to surface water by facilities near Stockton, ranked by pounds discharged annually.

Total reported releases to surface water: 0 lbs

FacilityTop chemicalTo surface water (lbs/yr)Distance
OLDCASTLE PACIFIC STOCKTON
Nonmetallic Mineral Product · CRH AMERICAS INC
STOCKTON, CA95206
Lead compounds05.4 mi
CONCRETE INC
Nonmetallic Mineral Product · KNIFE RIVER CORP
STOCKTON, CA95203
——2.2 mi
GAF MATERIALS MFG LLC
Petroleum · G HOLDINGS INC
STOCKTON, CA95215
——5.4 mi
KENT'S OIL SERVICE INC.
Petroleum Bulk Terminals · KNIFE RIVER CORP
STOCKTON, CA95205
——3.5 mi
SCHUFF STEEL CO
Fabricated Metals · INNOVATE CORP
STOCKTON, CA95206
——2.9 mi

Source: EPA Toxic Release Inventory (TRI) 2023

Site context

Superfund sites within 10 miles of Stockton

Superfund sites nearby

Federally tracked hazardous-waste sites on the EPA National Priorities List. Proximity does not necessarily indicate tap-water contamination — the connection depends on hydrology and treatment.

Source: EPA Superfund National Priorities List

Environmental Risk

Flood & disaster history

10
Declared disasters
Mar 2023
Most recent
Flood
Most common type

San Joaquin County has experienced 10 federally declared disasters since 1980. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.

Mar 2023
SEVERE WINTER STORMS, FLOODING, LANDSLIDES, AND MUDSLIDES
Flood FEMA #3592
Jan 2023
SEVERE WINTER STORMS, FLOODING, LANDSLIDES, AND MUDSLIDES
Flood FEMA #4683
Jan 2023
SEVERE WINTER STORMS, FLOODING, AND MUDSLIDES
Flood FEMA #3591
Apr 2017
SEVERE WINTER STORMS, FLOODING, AND MUDSLIDES
Flood FEMA #4308
Sep 2005
HURRICANE KATRINA EVACUATION
Hurricane FEMA #3248
Feb 1986
SEVERE STORMS & FLOODING
Flood FEMA #758
Filter Recommendations

Recommended water filters

Based on contaminants detected in Stockton's water supply, we recommend the following filter types.

🧪
For PFAS
Reverse Osmosis or Activated Carbon Block
PFAS compounds exceed EPA maximum contaminant levels
🔧
For Copper
Reverse Osmosis or KDF Filter
Copper exceeds the EPA action level of 1.3 mg/L
All Tested Contaminants

Full contaminants report

Contaminant Detected Level EPA Limit Unit Category Status
Lead (90th percentile) 0.0 15 ppb Inorganic Safe
Copper (90th percentile) 1.50 1.3 mg/L Inorganic Over Limit
11Cl-PF3OUdS ND HI µg/L PFAS Not Detected
4:2 FTS ND HI µg/L PFAS Not Detected
6:2 FTS ND HI µg/L PFAS Not Detected
8:2 FTS ND HI µg/L PFAS Not Detected
9Cl-PF3ONS ND HI µg/L PFAS Not Detected
ADONA ND HI µg/L PFAS Not Detected
HFPO-DA ND 0.01 µg/L PFAS Not Detected
lithium ND HI µg/L PFAS Not Detected
NEtFOSAA ND HI µg/L PFAS Not Detected
NFDHA ND HI µg/L PFAS Not Detected
NMeFOSAA ND HI µg/L PFAS Not Detected
PFBA ND HI µg/L PFAS Not Detected
PFBS 0.009 HI µg/L PFAS Detected
PFDA ND HI µg/L PFAS Not Detected
PFDoA ND HI µg/L PFAS Not Detected
PFEESA ND HI µg/L PFAS Not Detected
PFHpA ND HI µg/L PFAS Not Detected
PFHpS ND HI µg/L PFAS Not Detected
PFHxA 0.004 HI µg/L PFAS Detected
PFHxS 0.005 HI µg/L PFAS Detected
PFMBA ND HI µg/L PFAS Not Detected
PFMPA ND HI µg/L PFAS Not Detected
PFNA ND HI µg/L PFAS Not Detected
PFOA 0.008 0.004 µg/L PFAS Over MCL
PFOS 0.013 0.004 µg/L PFAS Over MCL
PFPeA 0.003 HI µg/L PFAS Detected
PFPeS ND HI µg/L PFAS Not Detected
PFTA ND HI µg/L PFAS Not Detected
PFTrDA ND HI µg/L PFAS Not Detected
PFUnA ND HI µg/L PFAS Not Detected
Data source: EPA SDWIS, UCMR 5, local utility CCR.
Lead Level History

Lead level trend (90th percentile)

EPA action level: 15 ppb
↗ Lead has increased by 0.8 ppb from 1992 (2.2 ppb) to 2026 (3.0 ppb).
Copper Level History

Copper level trend (90th percentile)

EPA action level: 1.3 mg/L
↗ Copper has increased by 0.135 mg/L from 2001 (1.370 mg/L) to 2022 (1.505 mg/L).
Contaminant Rankings

See how Stockton compares by contaminant

Explore where Stockton ranks among all California cities for specific contaminants.

Pb
Lead in California
Cities ranked by 90th percentile lead level (ppb)
→
PF
PFAS in California
Cities ranked by PFAS compounds detected
→
Cu
Copper in California
Cities ranked by 90th percentile copper level (mg/L)
→
Infrastructure

Water source & infrastructure

Primary Source
Surface Water
Operator
Local Government
Population Served
223,400
Water Systems
68
Source breakdown
Groundwater
57
Purchased Surface Water
5
Surface Water
4
Purchased Groundwater
2
Water Source

Where Stockton's water comes from

Surface Water

Stockton's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.

Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards.

These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge.

The system is operated by local government ownership and serves approximately 223,400 people through 68 water systems.

Local Hydrology

Water bodies near Stockton

Stockton is located near 1 notable water body. As a surface water system, these water bodies may directly influence the city's drinking water supply.

San Joaquin R Bl Garwood Bridge A Stockton
river
Infrastructure

Water systems serving Stockton

System Name PWSID Population Source
CITY OF STOCKTON CA3910012 191,302 SW
SAN JOAQUIN COUNTY - LINCOLN VILLAGE CA3910010 5,990 SWP
CDCR CALIFORNIA HEALTH CARE FACILITY CA3910803 5,551 SWP
SAN JOAQUIN COUNTY-MOKELUMNE ACRES CA3910017 3,802 GW
SAN JOAQUIN COUNTY - COLONIAL HEIGHTS CA3910002 1,841 SWP
OAKWOOD LAKE WATER DISTRICT-SUBDIVISION CA3910023 1,479 GW
FAIROAKS PWS #44 CA3901348 1,172 GW
SAN JOAQUIN COUNTY-RAYMUS VILLAGE CA3910014 1,086 GW
SAN JOAQUIN COUNTY - THORNTON CA3910009 964 GW
SAN JOAQUIN COUNTY - WILKINSON MANOR CA3910024 851 GW
STOCKTON VERDE MOBILE HOME PARK CA3910020 711 GW
MORADA ESTATES N PWS #46 CA3901337 426 GW
BEL AIR MOBILE ESTATE CA3900907 325 GW
SANTOS RANCH PWS #5-CSA #35 CA3901216 320 GW
SAN JOAQUIN WATER WORKS #2 CA3901092 310 GW
MORADA ESTATES PWS CA3900722 290 GW
PEPPERMINT CREEK MHP CA5500116 280 SW
ROUGH & READY VILLAGE CA2900530 268 GW
CLEMENTS WATER WORKS #43 CA3900504 264 GW
CAL 20 VILLAGE AND MEADOW POINTE PARK CA1700595 255 GW
SHADED TERRACE PWS CA3900720 238 GW
TWIN OAKS MOBILE PARK CA3901074 238 GW
KING ISLAND TRAILER PARK WATER SYSTEM CA3901114 236 GW
ELKHORN ESTATES WATER SYSTEM CA3900724 234 GW
ACAMPO WATER SYSTEM CA3901303 231 GW
CAPELL VALLEY ESTATES CA2800543 208 SW
CASA DE AMIGOS MANUFACTURED HOUSING COMM CA5000060 204 GW
SAN JUAN VISTA CA3901215 201 GW
BETHEL ISLAND MHC CA0707575 185 GW
CARIBOU MOBILE PARK PWS CA3900568 180 GW
GAYLA MANOR PWS CA3900563 178 GW
PAR COUNTRY ESTATES CSA-16 CA3901172 178 GW
RANCHO SAN JOAQUIN WATER SYS CA3900558 172 GW
SECURITY MHP CO0121750 150 GW
FAIRWAY ESTATES PWS CSA-18 CA3901075 149 GW
MULBERRY MHP CA5000072 148 GW
CORRAL HOLLOW PWS CA3900702 145 GW
PINE GROVE TRAILER PARK CA0800800 142 GW
GOLD BEACH PARK CA0900102 134 GW
MOBILE VILLAS TRAILER PARK CA3901081 130 GW
WILKINSON MANOR A-ZONE PWS CA3901159 125 GWP
QUIET OAKS MOBILE HOME PARK CA3701341 120 GW
BIG WHEEL MOBILE HOME PARK CA3900637 120 GW
AMBERWOOD ESTATES, LLC CA4500200 120 GW
SPRING CREEK ESTATES PWS CA3900927 119 GW
MORADA MANOR WATER SYSTEM CA3900523 112 GW
DEL RIO EAST HOA WATER SYSTEM CA5000099 110 GW
WALNUT ACRES CA3901113 106 GW
MORADA ACRES WATER SYSTEM CA3900512 105 GW
CHERRY LANE TRAILER PARK CA3900983 100 GW
DESERT MOBILE HOME ESTATES OR4101138 100 GW
MAURLAND MANOR WATER SYSTEM CA3900543 92 GWP
A1 WINSTONS MOBILE HOME PARK CA3900606 75 GW
WAYSIDE MOTEL APARTMENTS WTR SYS CA3900835 70 GW
SUNNYSIDE ESTATES WATER SYSTEM CA3900714 69 SWP
MARY LOU MOBILE HOME PARK CA1000265 68 GW
EVERGREEN MOBILE ESTATES CA4900728 65 GW
FOREST POINT MHC CA0300024 62 GW
OAKMONT WATER SYSTEM CA4300526 61 SWP
ALMOND PARK WATER SYSTEM CA3900517 60 GW
EL RIO MOBILE HOME PARK CA3900569 60 GW
RENO SAHARA TRAILER PARK NV0000701 60 GW
15TH AVENUE CA1600293 50 GW
STOCKTON EAST WATER DISTRICT CA3910006 50 SW
WINE COUNTRY APARTMENTS CA3900559 40 GW
ENCLAVE AT THE DELTA CA3901304 39 GW
FREMONT ONE CA3901474 39 GW
V & P TRAILER COURT WATER SYSTEM CA3900732 35 GW
Regional Comparison

How Stockton compares

Full California rankings →

Stockton's score of 33.3/100 is below the average of 57/100 among major California cities. It outscores 3 of 10 nearby cities. 7 of 10 nearby cities score higher.

Stockton (this city)
33.3
Los Angeles
42.8
San Jose
28
Oakland
77.9
San Diego
39.7
Sacramento
31.2
California avg
57
Regional Comparison

Nearby cities

View California rankings →
Los Angeles
California
F
Score: 42.8 · 253 violations · 3.9M residents
View report →
San Jose
California
F
Score: 28 · 556 violations · 3.2M residents
View report →
Oakland
California
B
Score: 77.9 · 89 violations · 1.4M residents
View report →
San Diego
California
F
Score: 39.7 · 184 violations · 1.4M residents
View report →
Sacramento
California
F
Score: 31.2 · 1263 violations · 1.2M residents
View report →
Burlingame
California
A-
Score: 89.2 · 19 violations · 885K residents
View report →
Anaheim
California
C+
Score: 69.3 · 29 violations · 751K residents
View report →
Perris
California
A
Score: 92.6 · 3 violations · 667K residents
View report →
Fresno
California
F
Score: 33.2 · 1141 violations · 625K residents
View report →
Long Beach
California
C
Score: 64.5 · 53 violations · 467K residents
View report →
City Profile

About Stockton, CA

Wikipedia →

Stockton is a city in and the county seat of San Joaquin County, California, United States. It is the most populous city in the county, the 11th-most populous city in California and the 60th-most populous city in the U.S, with 320,804 residents at the 2020 census. The city is located on the San Joaquin River in the northern San Joaquin Valley, within California's Central Valley. It lies at the southeastern corner of a large inland river delta that isolates it from other nearby cities, such as Sacramento and the San Francisco Bay Area.

Economic Profile
$71,612
Median Income
$382,663
Median Home Value
$1,417/mo
Median Rent
7.7%
Unemployment
Community
33.2
Median Age
1,981
People / sq mi
18.3%
College Educated
51.7%
Homeownership

Learn more about your water

Guides and resources related to Stockton's water quality findings.

Copper Contaminant Profile
EPA action levels, health effects, and copper removal options.
Read more →
PFAS Contaminant Profile
Detailed profile on PFAS contamination in US water systems.
Read more →
PFAS Forever Chemicals Explained
Learn what PFAS are, how they get into water, and what filtration removes them.
Read more →
County Data

Explore water quality across San Joaquin

San Joaquin Water Quality Rankings
Compare all cities in the county — grades, violations, and contaminant data side by side.
→
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FAQ

Frequently asked questions

Is Stockton, CA tap water safe to drink?

Stockton's water quality earned a grade of F (33.3/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #690 out of 694 cities tested in California.

What contaminants are in Stockton's water?

Lead was measured at 0.0 ppb (90th percentile). 6 PFAS compounds were detected. 1004 violations are on record.

How is Stockton's water quality grade calculated?

The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.

Do I need a water filter in Stockton?

PFAS compounds exceed EPA limits — a reverse osmosis or activated carbon filter is recommended.

Where does Stockton's water come from?

Stockton's water is sourced from Surface water. The city has 68 water systems serving approximately 223,400 residents.

What health violations has Stockton's water system had?

Stockton has 261 health-based violations on record. The most recent violation was recorded in October 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 168 violations remain unresolved.

Why does Stockton have so many PFAS compounds in its water?

6 different PFAS "forever chemical" compounds were detected in Stockton's water supply during UCMR 5 testing. PFAS contamination often originates from proximity to military installations (AFFF firefighting foam), airports, industrial manufacturing sites, or wastewater treatment facilities. Some levels exceed the 2024 EPA maximum contaminant levels — a reverse osmosis or NSF-certified activated carbon filter is strongly recommended.

How does Stockton's water compare to other cities?

Stockton ranks #690 out of 694 cities in California (better than 1% of state cities) and #15604 out of 15744 cities nationally (1th percentile). The grade of F reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.