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Water Quality Answers

What is CHLORAMINE and are there any negative health effects from its presence in drinking water?

Chloramine is formed as a result of the reaction between applied chlorine and ammonia present in the natural water or ammonia that has been added to react with chlorine so that a combined chlorine (chloramine) residual will be formed. This practice has been used in municipal water treatment for over 70 years.

Chloramine is used principally in systems requiring a reduction in tastes and odors, or a reduction in disinfection byproducts, such as trihalomethanes (THMs). Particularly where the water supply contains phenol, free chlorine readily reacts to form chlorophenol, which has a very disagreeable taste and odor. More recently, many public water systems have found that chloramine can be used to reduce the THM level in their water.

The primary disadvantage of chloramine is that it is a much weaker and slower acting disinfectant than free chlorine. It is particularly weak for inactivating certain viruses. In water systems that use chloramine as the principal disinfectant,  ammonia is added at a point downstream from the initial chlorine application so that microorganisms, including viruses, will be exposed to the free chlorine for a short period before the chloramine is formed.

Hospitals and kidney dialysis centers must be alerted when chloramines are used for water supply disinfection. Cases of chloramine-induced hemolytic anemia in patients have been reported when their dialysis water was not appropriately treated. Otherwise, we know of no ill-health effects associated with the ingestion of chloraminated drinking water.

Chloramines can be removed from water with very low flow rates (5 to 10 minutes contact time) through shell-base activated carbon, followed by mineral zeolite media for residual ammonia adsorption.