Does use of chloramines in place of chlorine for secondary disinfection change the taste of drinking water?

reverse osmosis banner square

First of all...just what is chloramine? And why am I drinking it? More importantly...will it change the taste of my water? In regards to the taste, it's a common thought that you likely won't notice any change. However, all the above are great questions.

Chloramines have been used in the U.S. for drinking water disinfection for over 70 years. Chloramine use was prevalent in the 1930s (Spaulding 1929, Braidech 1931, Lyles 1931, Goehring 1931, and Ely 1933). A nationwide survey conducted in 1938 showed that 16 percent of municipal utilities used chloramines at some point in their treatment process (AWWA 1941). Chloramine use declined during WWII because of the inability to obtain ammonia (White 1986), and by 1959, the number of utilities using chloramines had decreased to 6 percent (Baker 1959). By the early 1960s, chloramine use had dropped to less than 3 percent (Durfor and Becker 1962).

In the early 1970s, researchers discovered that halogenated organics were formed during chlorination (Rook 1974, Bellar and Lichtenberg 1974). Subsequent toxicological studies classified some of these disinfection byproducts (DBPs) as possible human carcinogens (Kimura Ebert and Dodge 1971, Page, Harris, and Epstein 1976, Kuzma, Kuzma, and Buncher 1977). There has been resurgence of interest in chloramination over the last 30 years as utilities seek a means to provide secondary disinfection while limiting disinfection byproduct (DBP) formation. In 1979, EPA published the first regulations limiting DBPs in the National Interim Primary Drinking Water Regulations for Control of Trihalomethanes. A maximum contaminant level (MCL) for total trihalomethanes (TTHMs) was set at 100 µg/L.

As researchers began to evaluate alternative disinfectants to limit DBP formation, it was discovered that chloramines resulted in significantly less TTHM formation than free chlorine (Brodtman and Russo 1979 and Norman, Harms, and Looyenga 1980). Laboratory results, in which chloramines required much higher concentrations and longer contact time to achieve microbiological inaction levels comparable to chlorine, led EPA to impose a ban on use of chloramines (National Interim Primary Drinking Water Regulations, USEPA 1978). Field results, however, indicated a much higher chloramine biocidal efficiency than predicted by laboratory research (Shull 1981, Brodtman and Russo 1979, and Mitcham, Shelley, and Wheadon 1983).

These successful applications of chloramination in field tests convinced EPA to rescind the ban a year later (USEPA 1979). The discrepancy between lab and field results for chloramine biocidal efficiency has been theorized to result from the relative resistance of in situ and laboratory grew organisms, the method of chloramine application (lab tests were typically conducted with preformed chloramines), and the criteria for evaluating the effectiveness of a disinfectant.

In regards to the taste chloramines may or may not leave in your drinking water, most consumers will not notice a change in water taste by switching from chlorine to chloramines for water disinfection. However, in surface waters that contain phenol, chlorine oxidation can produce chlorophenol as a byproduct. This chemical, which can impart taste and odor problems in drinking water, is not formed by chloramines. Some of the odor complaints in drinking water that people associate with chlorine are actually due to chlorine byproducts generated by incomplete oxidation.

Reading next