- most widely used bacteria-killing agent for pool water; organic chlorine is more suitable than inorganic for pool use because it is generally easier to use, does not affect water balance as much and is non-clouding
- oxidizes ammonia and nitrogen compounds (swimmer and bather waste)
- member of the halogen family of sanitizers, its use in swimming pools is in the elemental form of a gas, or as a liquid, granular or tablet compound
