Another type of disinfection process, chloramination , has been in use since 1983 for a portion of ACWD's service area. In November of 1997, ACWD began providing chloramination treatment to most of Fremont, Newark and Union City as part of its long-range water quality program. Although chloramines help to make your water safe to drink, they are toxic to fish, reptiles and amphibians and must be removed from the water these animals live in. Unlike chlorine, chloramines do not dissipate rapidly from water, so you will have to take steps to remove them.
Chloramines are a combination of chlorine and ammonia, both of which are toxic to fish.
As chloramines break down, either naturally or through the use of dechlorination chemicals, ammonia is freed up. This ammonia can be removed from fish tanks or ponds by using commercial products available at pet supply stores. Biological filters, natural zeolites and pH control methods are also effective in reducing the toxic effects of ammonia. Chloramines affect saltwater fish in the same way they affect freshwater fish. Koi are just as susceptible to chloramines as other fish.