What is Strontium* and Why Does It Matter?

Strontium is a naturally occurring metal found in soil, rock, and groundwater. It belongs to the same chemical family as calcium, which means your body absorbs it similarly to calcium — storing it in bones and teeth. Most strontium in tap water comes from the natural weathering of minerals like celestite and strontianite. Industrial sources, including mining operations and some manufacturing facilities, can also release strontium into local water supplies.

Water systems pick up strontium as groundwater moves through rock formations rich in the mineral. Surface water sources can also carry it, especially in regions with strontium-bearing geology. Right now, strontium appears in 3,294 water systems across the United States, with an average level of 0.532 parts per billion (ppb). Some systems have recorded levels as high as 38.2 ppb — a significant jump from the average that's worth paying attention to.

At low levels, strontium poses minimal risk for most healthy adults. The concern grows for children and infants, whose developing bones absorb minerals at a much higher rate. Research reviewed by the EPA links high strontium exposure to skeletal problems in children, including interference with normal bone development. Stable strontium (the non-radioactive kind found in tap water) is different from radioactive strontium-90, which is a nuclear byproduct. Still, the EPA has flagged the stable form as a potential health concern at elevated levels, particularly for bottle-fed infants who consume large amounts of water relative to their body weight.

The EPA has proposed a maximum contaminant level (MCL) of 4,000 ppb for strontium in drinking water — a threshold that no system in this dataset exceeds. That sounds reassuring, and in terms of regulatory compliance, it is. But the proposed limit is based on preventing the most severe effects, not on long-term low-dose exposure for vulnerable groups like infants and young children. The EPA's own health reference level sits at 1,500 ppb for adults and just 300 ppb for children under one year old. None of the 3,294 systems in this data exceed the EWG's health guideline, which means the detected levels are currently within ranges considered acceptable. Still, parents of formula-fed infants may want to take a closer look at their specific local levels.

Geographically, strontium detections follow patterns tied closely to underlying geology. Texas leads all states with 390 affected systems, which makes sense given the state's extensive limestone and dolomite formations — rock types known to carry strontium. Illinois comes in second with 263 systems, followed by North Carolina (247), Ohio (148), and Iowa (142). These states share something in common: large portions of their water supplies draw from groundwater that travels through strontium-rich bedrock. The Midwest and Southeast tend to see higher natural mineral content in water overall, and strontium is part of that picture. If you live in one of these states and rely on well water, testing your water directly is the most reliable way to know your actual exposure level.

The good news is that strontium is not difficult to remove from drinking water. Reverse osmosis (RO) filtration is one of the most effective methods, removing up to 95–99% of dissolved strontium. Ion exchange systems — the same technology used in water softeners — also reduce strontium significantly. Standard carbon filters, like pitcher filters or basic faucet attachments, are not designed to remove dissolved metals like strontium and won't offer meaningful protection. If you're concerned about strontium, especially for a young child or infant, an under-sink reverse osmosis system is the most reliable solution for your drinking and cooking water. Echo Water's reverse osmosis systems are built specifically to handle the kind of dissolved minerals and metals that show up in tap water across these regions — giving you cleaner water without having to think twice about it.

Regulatory Standards for Strontium*

Cities With the Highest Strontium* Levels

States Most Affected by Strontium*

Frequently Asked Questions

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