Strontium-90 in Drinking Water: Complete Guide (2026)

What is Strontium-90 and Why Does It Matter?

STRONTIUM-90: A RADIOACTIVE CONTAMINANT IN YOUR TAP WATER

What Is Strontium-90 and How Does It Get Into Tap Water?

Strontium-90 is a radioactive form of the element strontium. It's produced during nuclear fission — the process that happens in nuclear power plants and during nuclear weapons testing. Unlike naturally occurring strontium, this radioactive version decays slowly over time, with a half-life of about 29 years. This means it stays in the environment for decades. Strontium-90 enters water supplies primarily through atmospheric fallout from nuclear weapons testing (which peaked during the Cold War) and from accidents at nuclear facilities. Once in the soil and groundwater, it behaves like calcium in the environment, binding to soil particles and gradually leaching into aquifers that feed municipal water systems. The contamination is particularly stubborn because the element persists in groundwater for many years.

Health Effects and Exposure Risks

Strontium-90 is dangerous because your body treats it like calcium. When you drink contaminated water, your body absorbs it and deposits it in bones and teeth, where it continues to emit radiation directly to your bone marrow and other tissues. The EPA and the Centers for Disease Control (CDC) are most concerned about effects on children, whose bones are still developing and who absorb minerals more readily than adults. Long-term exposure to strontium-90 increases the risk of bone cancer and leukemia, according to the EPA's health assessment. At the levels detected in U.S. water supplies — averaging 0.36 picocuries per liter (pCi/L) across affected systems — the risk is generally considered low. However, 20 water systems tested above the EPA's safety standard, with one system in Arkansas reaching 1.16 pCi/L. For vulnerable populations like infants and young children, even lower exposures warrant precaution.

The Regulatory Picture: EPA Standards vs. Health Guidelines

The EPA sets the Maximum Contaminant Level (MCL) for strontium-90 at 8 pCi/L. This is the legal limit water utilities must meet. However, the Environmental Working Group (EWG), which bases its recommendations on cancer risk assessments, suggests a much stricter health guideline of 0.5 pCi/L. This 16-fold difference reflects the EWG's more conservative approach to radioactive contaminants. Of the 56 water systems where strontium-90 was detected, 20 exceeded the EWG guideline, though most stayed below the EPA's legal limit. This gap between regulations and health recommendations is why families in affected areas should take extra precautions, even if their water utility reports compliance with EPA standards.

Where Strontium-90 Shows Up Most

Arkansas leads the nation with strontium-90 detected in 23 water systems, followed by Connecticut with 18 systems. California, Oklahoma, and Virginia round out the top five states. The concentration in Arkansas and Connecticut reflects these regions' proximity to areas that received heavy atmospheric fallout during the Cold War era. Arkansas's groundwater, which feeds many municipal systems, accumulated strontium-90 from decades of fallout and retains it due to the state's geology. Connecticut's situation is similar, with aging aquifers continuing to release the contaminant. If you live in these states, particularly in rural or suburban areas relying on groundwater, testing your water is especially important.

How to Remove Strontium-90 From Your Drinking Water

Strontium-90 requires specific filtration methods because it's radioactive and dissolved in water. Standard carbon filters won't remove it. Reverse osmosis systems are highly effective, removing 95-99% of radioactive contaminants including strontium-90 by forcing water through a semi-permeable membrane. Ion exchange resins, which swap radioactive ions for harmless ones, also work well for strontium-90 specifically. If you're in Arkansas, Connecticut, or California, or if your water test shows strontium-90 above 0.5 pCi/L, a reverse osmosis system under your sink or a whole-home filtration system provides reliable protection. Boiling water does not remove strontium-90 — it actually concentrates it. Contact your local water utility for a recent water quality report, and consider independent testing through a certified lab if you want confirmation of your specific water's strontium-90 levels.

Regulatory Standards for Strontium-90

Cities With the Highest Strontium-90 Levels

States Most Affected by Strontium-90

Frequently Asked Questions

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