Radionuclides
Combined Radium in U.S. tap water
463 public water systems across 31 U.S. states report Combined Radium in their annual Consumer Confidence Report. 16 sit at or above the federal limit.
What it is
Combined radium-226 and radium-228 — naturally occurring radioactive elements.
Why it's regulated
Long-term exposure above the federal limit increases the risk of bone cancer.
At or above the federal limit (16)
| Water system | Measured | vs. limit |
|---|---|---|
| Clarksville, TN 2024 annual report | 12 pCi/L | 2.4× the limit |
| Aurora, IL 2024 annual report | 8.95 pCi/L | 1.8× the limit |
| Broad Creek, MD 2024 annual report | 8 pCi/L | 1.6× the limit |
| Crofton Odenton, MD 2024 annual report | 8 pCi/L | 1.6× the limit |
| Indian Hills Camp — Jamul, Ca, CA 2023 annual report | 0–6.27 pCi/L | 1.3× the limit |
| Antelope Valley East Kern Water Agency — Palmdale, Ca, CA 2021 annual report | 5.2 pCi/L | 1.0× the limit |
| White Fence Farms Mwc No. 1 — Palmdale, Ca, CA 2021 annual report | 5.2 pCi/L | 1.0× the limit |
| White Fence Farms Mwc No.3 — Lancaster, Ca, CA 2021 annual report | 5.2 pCi/L | 1.0× the limit |
| Catoosa Utility District Authority, TN 2025 annual report | 5 pCi/L | 1.0× the limit |
| Chattanooga, TN 2025 annual report | 5 pCi/L | 1.0× the limit |
| East Ridge, TN 2025 annual report | 5 pCi/L | 1.0× the limit |
| Lookout Mountain, TN 2025 annual report | 5 pCi/L | 1.0× the limit |
| Red Bank, TN 2025 annual report | 5 pCi/L | 1.0× the limit |
| Rossville, TN 2025 annual report | 5 pCi/L | 1.0× the limit |
| Signal Mountain, TN 2025 annual report | 5 pCi/L | 1.0× the limit |
| Walker County, TN 2025 annual report | 5 pCi/L | 1.0× the limit |
Approaching the limit (4)
| Water system | Measured | vs. limit |
|---|---|---|
| Rochester, MN 2025 annual report | 4.9 pCi/L | 1.0× the limit |
| Baton Rouge, LA 2024 annual report | 4.81 pCi/L | 1.0× the limit |
| Carpenters Point, MD 2024 annual report | 4.1 pCi/L | 0.8× the limit |
| Granite Mhp, MD 2024 annual report | 4–4 pCi/L | 0.8× the limit |
Within the federal limit (438)
Showing 50 of 438. The full list is in the JSON API.
Frequently asked
+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.
+What is 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 (typically a running annual average or 90th percentile), not a single-sample spike.
+How many U.S. water systems have Combined Radium over the federal limit?
16 of the 463 public water systems on The Water Map report Combined Radium at or above its federal limit, spanning 31 U.S. states. The full list is on this page.
+How can I check if Combined Radium is in my city's tap water?
Search your city on The Water Map (https://www.thewatermap.com/) or browse the list on this page. Every U.S. public water utility is required to publish an annual Consumer Confidence Report that lists every contaminant it measured, including Combined Radium.