Radionuclides
Gross Alpha in U.S. tap water
186 public water systems across 31 U.S. states report Gross Alpha in their annual Consumer Confidence Report. 4 sit at or above the federal limit.
What it is
Gross alpha particle activity — a combined measure of alpha-emitting radioactive substances.
Why it's regulated
Long-term exposure above the federal limit increases cancer risk.
At or above the federal limit (4)
| Water system | Measured | vs. limit |
|---|---|---|
| Pomona, CA 2024 annual report | 0–2024 pCi/L | 134.9× the limit |
| Birmingham, AL 2024 annual report | 37.7 pCi/L | 2.5× the limit |
| Burbank, CA 2024 annual report | 0–16.9 pCi/L | 1.1× the limit |
| Albuquerque, NM 2024 annual report | 0.7 | 1.0× the limit |
Approaching the limit (2)
| Water system | Measured | vs. limit |
|---|---|---|
| Yuma, AZ 2025 annual report | 12.5 pCi/L | 0.8× the limit |
| Meridian, ID 2024 annual report | 12 pCi/L | 0.8× the limit |
Within the federal limit (105)
| Water system | Measured |
|---|---|
| Chula Vista Sweetwater, CA 2024 annual report | 0–11.1 pCi/L |
| Lincoln, NE 2025 annual report | 11 |
| Norman, OK 2024 annual report | 0–10.9 pCi/L |
| Edmond, OK 2024 annual report | 10.7 pCi/L |
| Broad Creek, MD 2024 annual report | 2.1–10.5 pCi/L |
| Crofton Odenton, MD 2024 annual report | 2.1–10.5 pCi/L |
| Beaver Run Mhp, MD 2024 annual report | 8.8 |
| Pasadena, CA 2023 annual report | 8 |
| El Monte, CA 2024 annual report | 0–7.8 pCi/L |
| Glendale, CA 2024 annual report | 7.45 pCi/L |
| Houston, TX 2023 annual report | 7 pCi/L |
| Ventura, CA 2023 annual report | 6.7 pCi/L |
| Baton Rouge, LA 2024 annual report | 6.6 pCi/L |
| Lubbock, TX 2024 annual report | 5.7 pCi/L |
| Simi Valley, CA 2024 annual report | 5.62 pCi/L |
| Irvine, CA 2023 annual report | 5.4 pCi/L |
| Mesa, AZ 2024 annual report | 0–5.4 |
| City of Hemet, CA 2024 annual report | 5.2 pCi/L |
| City of Menifee, CA 2024 annual report | 5.2 pCi/L |
| City of Murrieta, CA 2024 annual report | 5.2 pCi/L |
| City of Perris, CA 2024 annual report | 5.2 pCi/L |
| City of San Jacinto, CA 2024 annual report | 5.2 pCi/L |
| City of Temecula, CA 2024 annual report | 5.2 pCi/L |
| East Valley Service Area, CA 2024 annual report | 5.2 pCi/L |
| Mills Service Area, CA 2024 annual report | 5.2 pCi/L |
| Moreno Valley, CA 2024 annual report | 5.2 pCi/L |
| Salt Lake City, UT 2024 annual report | 2.4–5.2 pCi/L |
| Skinner Service Area, CA 2024 annual report | 5.2 pCi/L |
| Carmel, IN 2024 annual report | 5.1 pCi/L |
| City of Hialeah, FL 2023 annual report | 0–5 pCi/L |
| City of Homestead, FL 2023 annual report | 0–5 pCi/L |
| City of North Miami Beach, FL 2023 annual report | 0–5 pCi/L |
| Miami Dade, FL 2023 annual report | 0–5 pCi/L |
| Torrance, CA 2024 annual report | 0–5 pCi/L |
| Hesperia, CA 2024 annual report | 0–4.88 pCi/L |
| Salinas, CA 2024 annual report | 4.5 pCi/L |
| Arlington, TX 2024 annual report | 4 pCi/L |
| Chula Vista Otay, CA 2024 annual report | 0–4 pCi/L |
| Los Angeles LADWP, CA 2023 annual report | 4 pCi/L |
| Gilbert, AZ 2024 annual report | 3.9 pCi/L |
| Henderson, NV 2024 annual report | 3.9 pCi/L |
| Tucson, AZ 2024 annual report | 0–3.9 pCi/L |
| Ann Arbor, MI 2024 annual report | 3.75 pCi/L |
| Cape Coral, FL 2024 annual report | 3.7 pCi/L |
| Centennial, CO 2023 annual report | 3.63 pCi/L |
| Denver, CO 2023 annual report | 3.4 pCi/L |
| City of Cupertino, CA 2024 annual report | 3.3 pCi/L |
| Escondido, CA 2024 annual report | 3.3 pCi/L |
| San Jose, CA 2024 annual report | 3.3 pCi/L |
| Santa Clara, CA 2024 annual report | 3.3 pCi/L |
Showing 50 of 105. The full list is in the JSON API.
Frequently asked
+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.
+What is 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 (typically a running annual average or 90th percentile), not a single-sample spike.
+How many U.S. water systems have Gross Alpha over the federal limit?
4 of the 186 public water systems on The Water Map report Gross Alpha at or above its federal limit, spanning 31 U.S. states. The full list is on this page.
+How can I check if Gross Alpha 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 Gross Alpha.