Is Clayton, CA Tap Water Safe to Drink?
Graded A- — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
86.6/100
waterverge.com Clayton, CA — Water Quality Report
Clayton's drinking water received a grade of A- (86.6 out of 100), indicating good water quality. The city's 3 water systems serve approximately 680 residents using purchased surface water.
Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 26 violations on record, including 5 health-based violations. 3 remain unresolved.
What to know about Clayton's water
Clayton ranks #226 out of 694 cities in California for water quality, placing it mid-range 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.
As a small community water system, Clayton may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Clayton, CA water safe to drink?
Clayton's drinking water has significant quality concerns based on EPA testing data. With a grade of A- (86.6/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 3 water systems serve approximately 680 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Clayton
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Clayton's water quality assessment. Grade: A- (86.6/100).
Contaminants: Lead and Copper Rule.
Federal disaster declaration (FEMA DR-4683). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-3591). Flood event — may have impacted local water infrastructure.
1 health-based. Contaminants: Coliform (TCR).
1 health-based. Contaminants: Coliform (TCR).
Key contaminant findings
Based on the most recent EPA sampling data for Clayton's water supply.
Well within EPA limits.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Violation history
Clayton's water system has 26 total violations on record, including 5 health-based violations. 3 remain unresolved. 1 violation was issued in the last 5 years.
Flood & environmental risk
Contra Costa 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 Suisun Bay A Mallard Is.
Where does Clayton's water come from?
Clayton's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 3 water systems serving approximately 680 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include Suisun Bay A Mallard Is (river).
What Clayton residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Clayton's water.
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.
Clayton'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.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Clayton
Industrial polluters nearby
Reported releases to surface water by facilities near Clayton, ranked by pounds discharged annually.
Total reported releases to surface water: 6,325 lbs
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
TESORO REFINING & MARKETING CO LLC MARTINEZ, CA94553 | Nitrate compounds (water dissociable; reportable only when in aqueous solution) | 5,793 | 9.8 mi |
MECS INC. MARTINEZ, CA94553 | Vanadium compounds | 404 | 8.9 mi |
SHELL CATALYSTS & TECHNOLOGIES - PITTSBURG PITTSBURG, CA94565 | Nitrate compounds (water dissociable; reportable only when in aqueous solution) | 121 | 6.0 mi |
USS-UPI LLC PITTSBURG, CA94565 | Chromium compounds (except for chromite ore mined in the Transvaal Region) | 8 | 7.3 mi |
GEORGIA-PACIFIC GYPSUM LLC ANTIOCH, CA94509 | — | — | 9.1 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Superfund sites within 10 miles of Clayton
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.
- CONCORD NAVAL WEAPONS STATION8.4 mi
Source: EPA Superfund National Priorities List
Flood & disaster history
Contra Costa 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.
Recommended water filters
Based on contaminants detected in Clayton's water supply, we recommend the following filter types.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.0 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 1.60 | 1.3 | mg/L | Inorganic | Over Limit |
Lead level trend (90th percentile)
Copper level (90th percentile)
Latest reading: 1.597 mg/L (1998)
EPA action level: 1.3 mg/L
See how Clayton compares by contaminant
Explore where Clayton ranks among all California cities for specific contaminants.
Water source & infrastructure
Where Clayton's water comes from
Clayton'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 private ownership and serves approximately 680 people through 3 water systems.
Water bodies near Clayton
Clayton is located near 1 notable water body. As a surface water system, these water bodies may directly influence the city's drinking water supply.
Water systems serving Clayton
| System Name | PWSID | Population | Source |
|---|---|---|---|
| CLAYTON PALMS WATER | CA0707603 | 549 | SWP |
| GATEWAY MOBILE HOME PARK | CA5200547 | 103 | GW |
| EVERGREEN MOTEL & MHP | CA3200114 | 28 | GW |
How Clayton compares
Full California rankings →Clayton's score of 86.6/100 is above the average of 57/100 among major California cities. It outscores 8 of 10 nearby cities.
Nearby cities
View California rankings →About Clayton, CA
Learn more about your water
Guides and resources related to Clayton's water quality findings.
Explore water quality across Contra Costa
Frequently asked questions
Is Clayton, CA tap water safe to drink?
Clayton's water quality earned a grade of A- (86.6/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #226 out of 694 cities tested in California.
What contaminants are in Clayton's water?
Lead was measured at 0.0 ppb (90th percentile). 26 violations are on record.
How is Clayton'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 Clayton?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Clayton's water come from?
Clayton's water is sourced from Purchased surface water. The city has 3 water systems serving approximately 680 residents.
What health violations has Clayton's water system had?
Clayton has 5 health-based violations on record. The most recent violation was recorded in October 2024. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 3 violations remain unresolved.
How does Clayton's water compare to other cities?
Clayton ranks #226 out of 694 cities in California (better than 67% of state cities) and #4620 out of 15744 cities nationally (71th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.