Chromium is a metal from natural deposits and industrial processes. It enters water through runoff. The toxic form, chromium-6, can cause cancer and organ damage.

Chromium exists in two main forms: chromium-3, an essential nutrient, and chromium-6, a toxic variant. While naturally occurring in some rocks, industrial processes like steel production and leather tanning are significant sources. The EPA regulates total chromium in drinking water, measured in parts per billion (ppb), but doesn't distinguish between forms. Chromium can be removed from water through methods such as ion exchange and reverse osmosis. Regular testing is crucial for maintaining safe water quality.