Water Quality: San Marcos, CA
2 water systems • 113,596 people served
Multiple Health ViolationsWater Quality Summary
San Marcos is served by 2 public water systems with a combined service population of 113,596 people, and has 182 EPA Safe Drinking Water Act violations on record. Critically, 53 of those are health-based violations, meaning one or more contaminants were detected above EPA-established safe levels — a serious public health concern. San Marcos's violation count is 279% above the national average for California. Contaminants associated with violations include Lead, Selenium.
Contaminants Found
Causes neurological damage, developmental delays in children, and kidney damage in adults even at low exposure levels.
Common source: Old plumbing pipes, lead solder, brass fixtures
EPA limit: Action Level: 0.015 mg/L (15 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 San Marcos
| System Name | PWSID | Source | Population | Violations |
|---|---|---|---|---|
| VALLECITOS WD | CA3710002 | Surface Water | 113,500 | 1 |
| OCOTILLO OASIS, LLC | CA3700291 | Groundwater | 96 | 181 |
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.