What is Strontium-90* and Why Does It Matter?

Strontium-90 is a radioactive form of the element strontium. It doesn't occur naturally — it's a byproduct of nuclear weapons testing and nuclear reactor accidents. When atomic bombs were tested above ground during the 1940s through 1960s, they released strontium-90 into the atmosphere. That fallout settled into soil and water sources across the globe, where it still lingers today. Nuclear plant accidents, like Chernobyl and Fukushima, added more. In some areas, strontium-90 also leaches from contaminated industrial sites into groundwater.

Once strontium-90 enters the body, it behaves like calcium. Your bones can't tell the difference. They absorb it and store it, which is exactly the problem. The radiation it emits damages bone marrow and surrounding tissue over time. Long-term exposure is linked to bone cancer and leukemia, according to the EPA and the World Health Organization. Children are especially vulnerable because their bones are still developing and absorb minerals — including strontium-90 — at higher rates than adults. There is no known safe level of exposure to radioactive contaminants. Every additional unit of radiation carries some added risk.

The EPA does not set a specific legal limit for strontium-90 on its own. Instead, it falls under the agency's broader beta particle radiation standard of 4 millirems per year. The Environmental Working Group (EWG) takes a stricter position, setting a health guideline of 0.15 pCi/L (picocuries per liter) based on a one-in-one-million cancer risk threshold. Of the 27 water systems where strontium-90 was detected, 9 exceeded that EWG guideline. The average detected level was 0.376 pCi/L — more than twice the EWG limit. The highest recorded level reached 0.75 pCi/L, five times above what the EWG considers safe. That gap between legal compliance and actual health protection is significant.

Geographically, Arkansas accounts for the majority of detections, with 18 affected water systems — far more than any other state. Connecticut follows with 4 systems, Oklahoma with 3, and California with 2. Arkansas's high numbers likely reflect a combination of legacy fallout deposition patterns and the state's reliance on groundwater sources, which can concentrate radioactive particles over time. Connecticut's detections are consistent with the Northeast's history of nuclear research facilities and aging infrastructure. Oklahoma and California detections are smaller in number but worth monitoring, particularly in communities drawing from older or less-treated groundwater supplies. If you live in any of these states, checking your local water utility's annual Consumer Confidence Report is a smart first step.

The good news is that strontium-90 can be effectively removed from drinking water. Reverse osmosis (RO) filtration is the most reliable method, removing up to 95% or more of radioactive particles including strontium-90. Ion exchange systems — which swap harmful ions in water for harmless ones — also perform well against this contaminant. Standard carbon filters and pitcher-style filters are not designed to remove radioactive particles, so they won't help here. If your water tests above the EWG guideline, a point-of-use reverse osmosis system installed under your kitchen sink is the most practical solution for protecting your drinking and cooking water. Echo Water's reverse osmosis systems are built to address exactly these kinds of contaminants, giving you filtered water directly at the tap without complicated installation. If you're in Arkansas, Connecticut, Oklahoma, or California — or simply unsure what's in your water — getting a water quality test is the most informed place to start. Knowing your numbers puts you in control.

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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