Radionuclides · 2025
Combined Radium in Contra Costa Water District, CA tap water
Contra Costa Water District, CA's 2025 Combined Radium measurement is below the federal limit of 5 PCI/L (MCL).
The measurement
| Statistic | Value | Federal limit |
|---|---|---|
Highest single sample Entry point | 0.495 PCI/L | 5 PCI/L MCL |
Average Source water | 0.19072000000000003 PCI/L | 5 PCI/L MCL |
Highest single sample Source water | 0.622 PCI/L | 5 PCI/L MCL |
Average Entry point | 0.304 PCI/L | 5 PCI/L MCL |
Verbatim from Contra Costa Water District, CA's 2025 Consumer Confidence Report — source document ↗
About Combined Radium
Combined radium-226 and radium-228 — naturally occurring radioactive elements.
Long-term exposure above the federal limit increases the risk of bone cancer.
How Contra Costa Water District, CA compares
5 of the 252 systems measuring Combined Radium on The Water Map have it at or above the federal limit:
Nearby systems also reporting Combined Radium:
People also ask
+Is there Combined Radium in Contra Costa Water District, CA tap water?
Yes — Contra Costa Water District, CA's 2025 Consumer Confidence Report lists Combined Radium at 0.304 PCI/L. Contra Costa Water District, CA's 2025 Combined Radium measurement is below the federal limit of 5 PCI/L (MCL).
+What's the federal limit for Combined Radium in drinking water?
The federal MCL for Combined Radium is 5 PCI/L. The EPA enforces this against the regulated reporting statistic (running annual average or 90th percentile), not a single-sample spike.
+What is Combined Radium?
Combined radium-226 and radium-228 — naturally occurring radioactive elements. Long-term exposure above the federal limit increases the risk of bone cancer.
+Which other U.S. cities have Combined Radium over the federal limit?
5 of the 252 systems on The Water Map measuring Combined Radium report it at or above the federal limit. Examples include West Covina, CA, Albuquerque, NM, City of Baltimore, MD.
+Where does this Combined Radium measurement come from?
This page reproduces the Combined Radium 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.