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Portland Water Bureau

From forest to faucet, we deliver the best drinking water in the world.


1120 SW Fifth Ave, Suite 600, Portland, OR 97204

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Chloramine in Drinking Water

The Portland Water Bureau delivers high quality drinking water that meets or exceeds all state and federal safe drinking water standards. The Portland Water Bureau has been using chloramine as its disinfectant residual since 1957 for public health protection. Approximately half of the country’s surface water systems use chloramine as a disinfectant. 

Our treatment process begins with high-quality chlorine as a primary disinfectant, which kills organisms in our source water. Then we add ammonia to form chloramine, which is a longer lasting secondary disinfectant than chlorine alone. Chloramines form fewer regulated disinfection byproducts, compared to chlorine. This treatment helps to keep bacteria from re-growing in our distribution system. Because chlorine breaks down more quickly than chloramine, using chloramine allows us to use a lower level of chlorine.

There is a significant amount of on-going research by many agencies worldwide regarding best disinfection practices for control of microorganisms in drinking water and minimization of chemical disinfection by-products. We continually monitor that research and the latest information on water disinfection practices.

The Portland Water Bureau reports its use of chloramine in the annual Drinking Water Quality Report, under Disinfectant Residual as the total chlorine residual, in the table on pages 5 and 6. The range in 2014 was less than 0.1 part per million to 2.72 parts per million. This falls below the EPA’s maximum residual disinfectant level of 4 parts per million.

Chloramine treatment is one of the reasons the Portland Water Bureau serves safe and high-quality water. As with chlorinated water, chloraminated water is safe for drinking and general use by people and animals. However, it must be removed for use by fish and amphibians. Treatment products are readily available at aquarium supply stores.