Water Quality: Napa, CA
15 water systems • 87,861 people served
Multiple Health ViolationsWater Quality Summary
Napa is served by 15 public water systems with a combined service population of 87,861 people, and has 177 EPA Safe Drinking Water Act violations on record. Critically, 71 of those are health-based violations, meaning one or more contaminants were detected above EPA-established safe levels — a serious public health concern. Napa's violation count is 269% above the national average for California. Contaminants associated with violations include Arsenic, E. coli, Gross Alpha, Stage 2 DBP, TTHM.
Contaminants Found
Long-term exposure increases risk of skin, bladder, and lung cancers, as well as cardiovascular and neurological effects.
Common source: Natural rock deposits, agricultural pesticides, industrial waste
EPA limit: 0.010 mg/L (10 ppb)
Causes gastrointestinal illness; certain strains (e.g., O157:H7) can cause severe kidney failure and death.
Common source: Fecal contamination from humans or animals entering the water supply
EPA limit: Zero (no E. coli permitted in drinking water)
Alpha-emitting radioactive particles increase cancer risk, particularly from bone and other internal cancers.
Common source: Natural uranium and radium in geological formations
EPA limit: 15 pCi/L (excluding radon and uranium)
Trihalomethanes and haloacetic acids that increase cancer risk and may cause adverse reproductive outcomes.
Common source: Chlorine disinfection reacting with natural organic matter in source water
EPA limit: TTHM: 0.080 mg/L; HAA5: 0.060 mg/L
Total trihalomethanes are linked to increased risk of bladder cancer and adverse reproductive outcomes.
Common source: Reaction of chlorine disinfectants with naturally occurring organic matter in water
EPA limit: 0.080 mg/L (80 ppb)
Haloacetic acids are associated with increased cancer risk and potential reproductive and developmental effects.
Common source: Reaction of chlorine disinfectants with organic matter in treated water
EPA limit: 0.060 mg/L (60 ppb)
Water Systems Serving Napa
| System Name | PWSID | Source | Population | Violations |
|---|---|---|---|---|
| NAPA, CITY OF | CA2810003 | Surface Water | 84,804 | 3 |
| BERRYESSA HIGHLANDS | CA2810013 | Surface Water | 715 | 50 |
| CIRCLE OAKS WATER DISTRICT | CA2800521 | Surface Water | 500 | 2 |
| BERRYESSA ESTATES (LBRID) | CA2800526 | Surface Water | 474 | 13 |
| BERRYESSA PINES WATER SYSTEM | CA2810009 | Surface Water | 261 | 16 |
| MEYERS WATER CO. | CA2800530 | Groundwater | 250 | 6 |
| HESS WINERY | CA2801016 | Groundwater | 250 | 4 |
| SPANISH FLAT WATER DISTRICT | CA2810014 | Surface Water | 230 | 13 |
| NAPA RIVER RANCH | CA2800531 | Groundwater | 70 | 35 |
| RIVER RANCH FARM WORKER CENTER | CA2800035 | Groundwater | 66 | 0 |
| MONDAVI FARM WORKER CENTER | CA2800040 | Groundwater | 66 | 0 |
| CALISTOGA FARM WORKER CENTER | CA2800039 | Groundwater | 65 | 0 |
| MILTON ROAD WATER COMPANY | CA2801080 | Groundwater | 44 | 21 |
| LITTLE LAKE MOBILE HOME PARK | CA2300705 | Groundwater | 38 | 4 |
| R RANCH AT THE LAKE | CA2800593 | Groundwater | 28 | 10 |
Concerned About Your Water?
A home water filter can remove common contaminants. NSF-certified filters are tested against EPA standards.
Consider a reverse osmosis system for comprehensive filtration or a carbon filter for basic improvement.
Other Cities in California
Data Sources
Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). Data includes all recorded violations for active community water systems.