Silver is a metal that enters water from industrial processes and photography. It's used in water treatment but can cause skin discoloration if consumed in large amounts.

Silver occurs naturally in the environment but is primarily released into water through industrial waste and photographic processing. It's measured in parts per billion (ppb) using atomic absorption spectroscopy. While silver is sometimes used as a water disinfectant, excessive exposure can lead to argyria, a permanent bluish-gray discoloration of the skin. Silver nanoparticles in water may also impact aquatic ecosystems. The EPA has set a secondary standard of 100 ppb for silver in drinking water.