Water Quality: Modesto, CA
16 water systems • 239,487 people served
Multiple Health ViolationsWater Quality Summary
Modesto is served by 16 public water systems with a combined service population of 239,487 people, and has 37 EPA Safe Drinking Water Act violations on record. Critically, 6 of those are health-based violations, meaning one or more contaminants were detected above EPA-established safe levels — a serious public health concern. Modesto's violation count is 23% below the national average for California. Contaminants associated with violations include Haloacetic Acids, Selenium.
Contaminants Found
Linked to increased cancer risk and potential reproductive and developmental effects with long-term exposure.
Common source: Reaction of chlorine disinfectants with organic matter in treated water
EPA limit: 0.060 mg/L (60 ppb)
Hair loss, nail brittleness, and nervous system damage at elevated concentrations.
Common source: Natural geological deposits, mining discharges, oil refinery waste
EPA limit: 0.05 mg/L (50 ppb)
Water Systems Serving Modesto
| System Name | PWSID | Source | Population | Violations |
|---|---|---|---|---|
| MODESTO, CITY OF | CA5010010 | Surface Water | 218,771 | 0 |
| CITY OF MODESTO - SALIDA | CA5010005 | Groundwater | 14,537 | 14 |
| CITY OF MODESTO - DEL RIO | CA5010029 | Groundwater | 1,327 | 0 |
| CITY OF MODESTO - SOUTH TURLOCK | CA5010023 | Groundwater | 1,099 | 0 |
| CITY OF MODESTO - GRAYSON | CA5010033 | Groundwater | 914 | 2 |
| HILLSVIEW HOMES | CA5010007 | Groundwater | 887 | 6 |
| RIVERDALE PARK TRACT CSD | CA5000019 | Groundwater | 610 | 8 |
| BUENA VISTA MIGRANT CENTER | CA4400763 | Groundwater | 455 | 4 |
| PARK HEIGHTS MUTUAL WATER CO | CA5000017 | Groundwater | 250 | 0 |
| CITY OF MODESTO - WALNUT MANOR | CA5010031 | Groundwater | 175 | 0 |
| CITY OF MODESTO - NORTH TURLOCK | CA5010034 | Groundwater | 172 | 0 |
| CITY OF MODESTO - CENTRAL TURLOCK | CA5010035 | Groundwater | 119 | 0 |
| MORNINGSIDE MOBILEHOME PARK | CA5000054 | Groundwater | 67 | 1 |
| COUNTRY WESTERN MHRV | CA5000080 | Groundwater | 55 | 1 |
| RIVER ROAD MUTUAL WATER COMPANY | CA5000020 | Groundwater | 26 | 1 |
| MODESTO IRRIGATION DISTRICT | CA5010038 | Surface Water | 23 | 0 |
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.