In the United States, the maintenance of what is called a "residual" of disinfectant that stays in the water distribution system while it is delivered to people's homes is required by the Environmental Protection Agency (EPA).
Both chlorine and chloramine react with other compounds in the water to form what are called "disinfection byproducts".
[4] Elsewhere, similar oversight agencies may set drinking water quality standards for chloramine.
[5][6] Nitrogenous disinfection by-products are liable to convert to nitrosamines by the action of chlorination and chloramination.
Chloramine must be removed from water prior to use in kidney dialysis machines because it can cause hemolytic anemia if it enters the blood stream.
[citation needed] The use of ultraviolet light for chlorine or chloramine removal is an established technology that has been widely accepted in pharmaceutical, beverage, and dialysis applications.
SFPUC determined that 1000 mg of vitamin C tablets, crushed and mixed in with bath water, completely remove chloramine in a medium-size bathtub without significantly depressing pH.
[citation needed] Most dialysis units now depend on granular activated carbon (GAC) filters, two of which should be placed in series so that chloramine breakthrough can be detected after the first one, before the second one fails.
Sodium thiosulfate is used to dechlorinate tapwater for aquariums or treat effluent from wastewater treatments prior to release into rivers[citation needed].
Treatment of tapwater requires between 0.1 and 0.3 grams of pentahydrated (crystalline) sodium thiosulfate per 10 L of water[citation needed].