San Marcos Water Quality
California
The tap water in San Marcos, California is served by 2 EPA-regulated water systems covering approximately 113,596 people. 53 health-based violations are on record, most recently for 1025 in 2023. Data source: EPA Safe Drinking Water Information System.
Drinking water in San Marcos, California is delivered through 2 EPA-regulated community water systems serving an estimated 113,596 people. Each system is tracked in the EPA Safe Drinking Water Information System (SDWIS) under the Safe Drinking Water Act, which requires testing for regulated contaminants, consumer notification of violations, and publication of an annual Consumer Confidence Report.
The SDWIS record for San Marcos shows 53 total violations across all 2 systems, of which 53 are health-based, meaning either a Maximum Contaminant Level (MCL) was exceeded or a required treatment technique was not followed. Contaminants cited in health-based violations include 1025, 1040. 5 TRI-reporting industrial facilities are also located within the city limits.
A past EPA violation does not mean the water is currently unsafe, utilities are required to notify customers and remediate under state primacy oversight. For current water-quality status and treatment practices, review your local utility's most recent Consumer Confidence Report or contact the California drinking water program. All records above reflect federal EPA SDWIS data and are not independently verified against state databases.
Community Water Systems
| System Name | Pop. Served | Violations | Status |
|---|---|---|---|
| VALLECITOS WD | 113,500 | 0 | Clean |
| OCOTILLO OASIS, LLC | 96 | 53 | Health |
Does this city have health-based water violations?
Health-based violations indicate contaminant levels that exceeded EPA maximum contaminant levels (MCLs). This does not necessarily mean water is currently unsafe.
| Contaminant | Begin Date |
|---|---|
| 1025 | 2023-04-01 |
| 1025 | 2023-04-01 |
| 1025 | 2023-01-01 |
| 1025 | 2023-01-01 |
| 1025 | 2021-10-01 |
| 1025 | 2021-10-01 |
| 1025 | 2021-07-01 |
| 1025 | 2021-07-01 |
| 1025 | 2021-04-01 |
| 1025 | 2021-04-01 |
| 1025 | 2021-01-01 |
| 1025 | 2021-01-01 |
| 1025 | 2021-01-01 |
| 1040 | 2019-09-03 |
| 1040 | 2019-09-03 |
| 1025 | 2017-10-01 |
| 1025 | 2017-10-01 |
| 1025 | 2017-07-01 |
| 1025 | 2017-07-01 |
| 1025 | 2017-04-01 |
| 1025 | 2017-04-01 |
| 1025 | 2017-01-01 |
| 1025 | 2017-01-01 |
| 1025 | 2016-10-01 |
| 1025 | 2016-10-01 |
| 1025 | 2016-07-01 |
| 1025 | 2016-07-01 |
| 1025 | 2016-04-01 |
| 1025 | 2016-04-01 |
| 1025 | 2016-01-01 |
| 1025 | 2016-01-01 |
| 1025 | 2015-10-01 |
| 1025 | 2015-10-01 |
| 1025 | 2015-07-01 |
| 1025 | 2015-07-01 |
| 1025 | 2015-04-01 |
| 1025 | 2015-04-01 |
| 1025 | 2015-01-01 |
| 1025 | 2015-01-01 |
| 1025 | 2014-10-01 |
| 1025 | 2014-10-01 |
| 1025 | 2014-07-01 |
| 1025 | 2014-07-01 |
| 1025 | 2014-04-01 |
| 1025 | 2014-04-01 |
| 1025 | 2014-03-01 |
| 1025 | 2014-03-01 |
| 1025 | 2013-11-01 |
| 1025 | 2013-11-01 |
| 1025 | 2013-09-01 |
TRI Facilities in San Marcos
| Facility | Total Releases |
|---|---|
| Sumitomo Electric Interconnect Products Inc | 393.7K lbs |
| Piercan USA Inc. | 11.1K lbs |
| Hughes Circuits Inc | 43 lbs |
| Hocking International Laboratories LLC | 0 lbs |
| Hollandia Dairy Inc | 0 lbs |
Frequently Asked Questions
Is San Marcos, California water safe to drink? ▼
How many water violations does San Marcos have? ▼
What contaminants were found in San Marcos water? ▼
How many water systems serve San Marcos? ▼
Where does San Marcos get its drinking water? ▼
Are there pollution sources near San Marcos? ▼
About This Data
Water system data comes from the EPA's Safe Drinking Water Information System (SDWIS). Violations are reported by state agencies to EPA and include both health-based (MCL exceedances) and monitoring/reporting violations.
A reported violation does not necessarily mean water is currently unsafe to drink. Many violations are resolved quickly, and public water systems are required to notify customers of significant issues. For current water quality, contact your local water utility.
TRI facility data comes from the EPA Toxic Release Inventory. Facilities shown are those that self-report to the TRI program. PlainEnviro presents this data without advocacy framing.
Read our methodology - how this data is sourced, computed, and verified.