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Disinfecting Water with Chloramine

To disinfect much of Santa Clara County's drinking water supply, the Santa Clara Valley Water District – like most water management agencies in the nation – uses a chemical compound known as chloramine.

Chloramine, a combination of chlorine and ammonia, is used effectively to prevent waterborne diseases.

The water district operates three water treatment plants that clean and purify water imported from the Sacramento-San Joaquin Delta or captured in one of our 10 reservoirs. The three plants can produce as many as 220 million gallons of water a day.

In order to reduce the growth of microorganisms or harmful bacteria, the district has been adding chloramine to the water supply since 1983.

Chloramine, when compared to chlorine, forms a significantly lower amount of “disinfection byproducts” such as trihalomethanes (THMs) and haloacetic acids (HAAs). Another disinfection byproduct, NDMA, has been detected on several occasions, but below the health advisory level established by the California Department of Health Services.

Chloraminated water is safe for drinking, bathing, cooking and all other daily uses. Chloramine doesn’t change the taste, smell or appearance of water.

Certain water users with sensitivities to chemicals may need to continue to take precautionary measures.

Dialysis patients: Chloramine, like any other chemical, must be removed from water prior to dialysis treatment. Medical centers that perform dialysis are responsible for purifying water that enters machines. People with home dialysis machines should consult their physician. Often, home dialysis service companies can make modifications if necessary. Dialysis patients may want to consult with the Trans Pacific Renal Network at (415) 472-8590 or visit its Web site at for more information.

Aquariums: Chloramine is toxic to both fresh- and salt-water fish, so it must be removed from water used in aquariums and fish ponds. That can be easily done by purchasing a dechlorinating chemical found at most pet supply stores.

If you have questions regarding chloramine, contact your local water provider or Bruce Cabral, the water quality unit manager for the Santa Clara Valley Water District, at (408) 265-2607, ext. 2796, or through e-mail, Bruce Cabral.