Bromate is a chemical byproduct formed when ozone or chlorine disinfects water containing bromide. It's regulated due to its potential to increase cancer risk.

Bromate forms when water treatment plants use ozone or chlorine to disinfect water containing naturally occurring bromide. While disinfection is crucial for eliminating harmful microorganisms, bromate is an unintended consequence. The EPA regulates bromate levels in drinking water, setting a maximum contaminant level of 0.010 mg/L. Water utilities monitor bromate using laboratory analysis techniques such as ion chromatography. To reduce bromate formation, treatment plants may adjust their disinfection processes or remove bromide before disinfection.