Strontium in Drinking Water: Health Risks, EPA Levels & Removal

What Is Strontium?

Strontium is a naturally occurring alkaline earth metal found in groundwater across the United States. It is chemically similar to calcium and enters water primarily through the dissolution of celestite (strontium sulfate) and strontianite (strontium carbonate) minerals in aquifer rock — the same kind of geology that produces elevated radium and uranium in many private wells. The EPA included strontium in the Unregulated Contaminant Monitoring Rule 3 (UCMR 3, 2013–2015) to assess its occurrence in public drinking water supplies.

Unlike many regulated contaminants, strontium does not have a federal maximum contaminant level (MCL). The EPA established a health reference level (HRL) of 1,500 µg/L based on available toxicological data. UCMR 3 data showed that strontium is one of the most frequently detected unregulated contaminants — present in approximately 99% of tested water systems, with about 7% exceeding the HRL.

How Strontium Gets Into Drinking Water

Strontium enters water supplies almost exclusively through natural geological processes. It dissolves from sedimentary rock formations — particularly limestone, dolomite, and gypsum deposits — as groundwater moves through the subsurface. Concentrations tend to be highest in:

• Groundwater systems in regions with carbonate bedrock, especially across the Midwest, Great Plains, and parts of the Southwest
• Areas with high mineral content in source water (hard water regions often have elevated strontium)
• Wells drawing from deep aquifers where water has had prolonged contact with mineral-bearing rock

Industrial sources of strontium in drinking water are uncommon but can include ceramic manufacturing, pyrotechnics production, and certain mining operations.

Health Effects

Bone and Skeletal Effects

Strontium’s primary health concern is its effect on bones. Because strontium is chemically similar to calcium, the body incorporates it into bone tissue. At normal dietary levels this is harmless, but elevated exposure can:

• Impair bone development in children — the most sensitive population. Growing bones absorb strontium more readily, potentially interfering with normal mineralization. See our baby and infant water safety guide for guidance on formula prep with strontium-rich water
• Reduce bone density at high concentrations by displacing calcium in bone matrix
• Affect dental development in children with prolonged exposure above the HRL

Other Effects

• Cardiovascular effects: Some epidemiological studies suggest associations between high strontium in drinking water and cardiovascular outcomes, though evidence is limited
• Kidney effects: At very high concentrations, strontium may affect renal function

The EPA’s 1,500 µg/L health reference level is based on protecting against adverse bone effects in children, the most sensitive endpoint.

EPA Regulation Status

Strontium does not have a federal MCL. After UCMR 3 monitoring, the EPA made a preliminary regulatory determination in 2016 that strontium met the criteria for regulation under the Safe Drinking Water Act. However, as of 2026, no MCL has been finalized. The 1,500 µg/L HRL serves as the primary reference point for evaluating exposure risk.

How to Remove Strontium from Drinking Water

The most effective removal methods for strontium include:

• Reverse osmosis (RO): Removes 95%+ of strontium. The most reliable point-of-use option — see the best reverse osmosis systems
• Ion exchange softeners: Water softeners that remove calcium also remove strontium, since both are divalent cations. See softeners vs filters for choosing between the two approaches
• Distillation: Effective but impractical for whole-house use
• Lime softening: Used by some municipal treatment plants

Standard activated carbon filters (pitcher filters, refrigerator filters) do not meaningfully reduce strontium.

Frequently Asked Questions

Is strontium in water dangerous?

At levels below the EPA health reference level of 1,500 µg/L, strontium in drinking water is generally not considered a significant health risk for adults. Children are more vulnerable because their developing bones absorb strontium more readily. If your water contains strontium above the HRL, a reverse osmosis system or water softener can reduce levels effectively.

How common is strontium in US drinking water?

Very common. UCMR 3 data (2013–2015) found strontium in approximately 99% of public water systems tested. However, only about 7% of systems exceeded the 1,500 µg/L health reference level. Concentrations are highest in groundwater systems in the Midwest and Great Plains.

Does boiling water remove strontium?

No. Boiling concentrates dissolved minerals including strontium. Reverse osmosis or ion exchange (water softener) systems are needed to reduce strontium levels.