Strontium is a metal found in rocks and soil that can enter water through erosion or industrial discharge. It can replace calcium in bones, affecting bone health.

Strontium occurs naturally but can also come from industrial sources like nuclear plants and electronics manufacturing. It's measured in parts per billion (ppb) in water. Chemically similar to calcium, strontium can accumulate in bones. While small amounts are harmless, high levels may affect bone development, especially in children. The EPA monitors strontium but hasn't set enforceable limits. Some water treatment methods can reduce strontium levels in drinking water.