Monochloramine

Monochloramine, a combination of chlorine and ammonia which is commonly known as "chloramine, " has been widely and successfully used as a drinking water disinfectant since the 1930s. While monochloramine is used rarely as a water system’s primary disinfectant, it is more often added into the distribution system to ensure that the water remains safe as it is delivered to your home. 

Monochloramine Use in the U.S.

The U.S. Environmental Protection Agency (EPA) estimates that more than 30 percent of the nation’s large water systems currently use monochloramine as at some point in their systems. That number is likely to rise as more communities seek to reduce exposure to potentially harmful byproducts that can form during the disinfection process.

Why Use Monochloramine?

Monochloramine is a disinfectant used to kill bacteria and other microbes as a part of drinking water treatment. While chlorine is the most commonly used primary disinfectant, an increasing number of water providers are using monochloramine to help them comply with new regulations. The new regulations are designed to limit certain “disinfectant byproducts” in finished water. These disinfection byproducts – which are potentially harmful to humans -- are formed when organic and inorganic matter in the water react with chlorine or other disinfectants.

Many water systems also favor the use of monochloramine because they experience fewer taste and odor complaints from customers than when they use chlorine.

Monochloramine and Kidney Dialysis

Monochloramine must be removed from the water used in the kidney dialysis process. Kidney dialysis patients can safely drink, cook, and bathe in monochloraminated water, but dialysis systems require some modifications to remove the monochloramine. Patients should check with their physician to be certain the necessary changes are made.

Monochloramine and Fish

Though safe for drinking by humans, monochloramine, like chlorine, is toxic to fish and other aquatic organisms at levels used for drinking water. Fish hobbyists or home aquarium owners must neutralize or remove monochloramine from water used in aquariums or ponds. Treatment products for this purpose are readily available at aquarium supply stores.

To avoid effects on aquatic life from monochloramine, de-chlorinating chemicals must be used if large volumes of monochloraminated water is discharged to rivers or lakes.