Public water system record
California Water Service - San Mateo
Serves San Mateo, Highlands and Baywood Park, San Mateo County, CA · 102,348 people served
Federal records show no health-based violations and no monitoring or reporting issues for California Water Service - San Mateo in the last ten years.
System profile
- Health-based violations, last 10 years
- 0
- Resolved
- 0
- Unresolved
- 0
- Any acute record
- No
- Monitoring issues, last 10 years
- 0
Key facts
- California Water Service - San Mateo buys its water from San Francisco Regional Water System.
- Most recent formal enforcement: compliance order (no penalty) by California, June 1993.
- Record on file since 1992, with 2 health-based violations before October 19, 2016.
- Lead pipe inventory: 0 lead and 220 unknown out of 26,354 service lines.
Check whether California Water Service - San Mateo serves your address
Health-based violations
Since October 2016Violation data reflects EPA records through March 2026. For the most current status, visit the EPA ECHO database.
None since October 2016, and no monitoring or reporting violations either.
Full record since 1992
EPA's records for California Water Service - San Mateo go back to 1992. Before October 19, 2016 they list 2 health-based violations (2 resolved) and no monitoring or reporting violations.
| Violations that began in | Health-based | Monitoring and reporting |
|---|---|---|
| 1990s | 2 | 0 |
Most recent health-based violation before October 19, 2016: Surface Water Treatment Rule, began June 1993, Resolved.
Show all 2 health-based violations before October 19, 2016
| Contaminant | Start date | Status |
|---|---|---|
|
Surface Water Treatment Rule
Treatment technique failure
|
Jun 1, 1993 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Oct 1, 1992 | Resolved |
Enforcement actions
California regulators took 1 formal enforcement action against California Water Service - San Mateo in 1993. The most recent was a compliance order (no penalty) in June 1993.
| Date | By | Action | Violations covered |
|---|---|---|---|
| Jun 30, 1993 | California | Compliance order (no penalty) | 1 violation (1 health-based): Surface Water Treatment Rule |
Where the water comes from
California Water Service - San Mateo buys its water from San Francisco Regional Water System. It lists no wells or intakes of its own.
Buys water from
- San Francisco Regional Water System Burlingame, CA
Annual water quality report
California Water Service - San Mateo must give its customers an annual water quality report (Consumer Confidence Report) by July 1, with the levels its tests found in the previous year.
Systems serving 10,000 or more people must mail or deliver the report to every customer, and from 2027 they must send it twice a year.
Find a posted report with EPA's Consumer Confidence Report search
Testing your own water
To test the water at your tap, or a private well this record does not cover, use a laboratory certified for drinking water by California.
Certified drinking water labs by state EPA guidance for private wells