Metals · 2025
Lead in California Water Service - San Mateo, CA tap water
California Water Service - San Mateo, CA's 2025 Lead measurement is below the federal limit of 15 UG/L (Al).
The measurement
| Statistic | Value | Federal limit |
|---|---|---|
Average Distribution | 4.490909090909091 UG/L | None set |
90th percentile Distribution | 6.920000000000011 UG/L | 15 UG/L Al |
Highest single sample Distribution | 111 UG/L | None set |
Verbatim from California Water Service - San Mateo, CA's 2025 Consumer Confidence Report — source document ↗
About Lead
A toxic metal that leaches into water from old service lines, solder, and plumbing fixtures.
There is no safe level of lead; it harms brain development in children and raises blood pressure in adults. The EPA sets an action level, not a health goal above zero.
How California Water Service - San Mateo, CA compares
5 of the 433 systems measuring Lead on The Water Map have it at or above the federal limit:
Nearby systems also reporting Lead:
People also ask
+Is there Lead in California Water Service - San Mateo, CA tap water?
Yes — California Water Service - San Mateo, CA's 2025 Consumer Confidence Report lists Lead at 6.920000000000011 UG/L. California Water Service - San Mateo, CA's 2025 Lead measurement is below the federal limit of 15 UG/L (Al).
+What's the federal limit for Lead in drinking water?
The federal Al for Lead is 15 UG/L. The EPA enforces this against the regulated reporting statistic (running annual average or 90th percentile), not a single-sample spike.
+What is Lead?
A toxic metal that leaches into water from old service lines, solder, and plumbing fixtures. There is no safe level of lead; it harms brain development in children and raises blood pressure in adults. The EPA sets an action level, not a health goal above zero.
+Which other U.S. cities have Lead over the federal limit?
5 of the 433 systems on The Water Map measuring Lead report it at or above the federal limit. Examples include Santa Rosa, CA, Atlanta, GA, City of San Jacinto, CA.
+Where does this Lead measurement come from?
This page reproduces the Lead entry from the 2025 Consumer Confidence Report published by the California Water Service - San Mateo, CA water utility — the annual drinking-water report every U.S. utility is required by federal law to publish. The original source document is archived at /water/ca/california-water-service-san-mateo/2025/source.