Strontium (Sr) and water

Strontium is a naturally occurring alkaline-earth element that commonly dissolves in water as Sr²⁺. Its concentration varies with local geology, groundwater residence time and the dissolution of minerals. Stable strontium and radioactive strontium isotopes require different assessment and monitoring.

Strontium in natural waters

Weathering of strontium-bearing minerals and interaction with carbonate, sulfate and other mineral deposits can contribute strontium to groundwater and surface water. Strontium is also a minor constituent of seawater, averaging about 8 mg/L. In freshwater, concentrations are highly variable and depend on the aquifer and water chemistry; a single “typical” value is not representative of all supplies.^[1]

The naturally occurring stable isotopes of strontium are not radioactive. Strontium-90 is a radioactive fission product and must be assessed as a radionuclide. Total strontium results alone do not establish whether radioactive strontium is present; use isotope-specific analysis where radiological sources are plausible.^[2]

Health considerations

Stable strontium is present in food and water, and ordinary environmental exposure is not generally associated with harmful effects. Very high exposure can affect bone development, especially in children with inadequate calcium and protein intake. National guidance and regulatory values differ; check the applicable drinking-water rules and do not treat a health reference level as a universal legal limit.^[1]

Strontium removal from water

Removal depends on the raw-water chemistry and the required finished-water concentration. Ion-exchange softening and lime softening have been evaluated at full-scale; reported performance varies, and lime-softening removal can track calcium removal. Reverse osmosis and nanofiltration can also reduce dissolved strontium, transferring it to a concentrate. Pilot testing should account for calcium, hardness, sulfate, alkalinity, membrane recovery and residuals management before a process is selected.^[3]^[4]

Last reviewed: 3 November 2026 by Lenntech.