Acetaldehyde is an organic compound found in air pollution and formed when chlorine reacts with organic matter in water. It's a potential carcinogen from industrial sources.

Acetaldehyde can enter drinking water through industrial discharges or form when chlorine disinfectants react with naturally occurring organic matter. It's typically measured using gas chromatography. While classified as a potential carcinogen, more research is needed on its specific health impacts at levels found in drinking water. Water treatment plants can reduce acetaldehyde formation by optimizing disinfection processes and removing organic precursors. Home carbon filters may also help reduce exposure.