Radionuclides · 2025
Gross Alpha in Contra Costa Water District, CA tap water
Contra Costa Water District, CA's 2025 Gross Alpha measurement is below the federal limit of 15 PCI/L (MCL).
The measurement
| Statistic | Value | Federal limit |
|---|---|---|
Average Entry point | 1.42 PCI/L | 15 PCI/L MCL |
Highest single sample Source water | 3.55 PCI/L | 15 PCI/L MCL |
Average Source water | 1.9769999999999999 PCI/L | 15 PCI/L MCL |
Highest single sample Entry point | 1.42 PCI/L | 15 PCI/L MCL |
Verbatim from Contra Costa Water District, CA's 2025 Consumer Confidence Report — source document ↗
About Gross Alpha
Gross alpha particle activity — a combined measure of alpha-emitting radioactive substances.
Long-term exposure above the federal limit increases cancer risk.
How Contra Costa Water District, CA compares
5 of the 246 systems measuring Gross Alpha on The Water Map have it at or above the federal limit:
Nearby systems also reporting Gross Alpha:
People also ask
+Is there Gross Alpha in Contra Costa Water District, CA tap water?
Yes — Contra Costa Water District, CA's 2025 Consumer Confidence Report lists Gross Alpha at 1.9769999999999999 PCI/L. Contra Costa Water District, CA's 2025 Gross Alpha measurement is below the federal limit of 15 PCI/L (MCL).
+What's the federal limit for Gross Alpha in drinking water?
The federal MCL for Gross Alpha is 15 PCI/L. The EPA enforces this against the regulated reporting statistic (running annual average or 90th percentile), not a single-sample spike.
+What is Gross Alpha?
Gross alpha particle activity — a combined measure of alpha-emitting radioactive substances. Long-term exposure above the federal limit increases cancer risk.
+Which other U.S. cities have Gross Alpha over the federal limit?
5 of the 246 systems on The Water Map measuring Gross Alpha report it at or above the federal limit. Examples include San Diego, City of, CA, Birmingham, AL, Rancho Estates Mutual Water Co., CA.
+Where does this Gross Alpha measurement come from?
This page reproduces the Gross Alpha entry from the 2025 Consumer Confidence Report published by the Contra Costa Water District, 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/contra-costa-water-district/2025/source.