Canadian Water and Wastewater Association eBulletin

Final guideline for Canadian drinking water quality for chloramines

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The guidelines state: "It is not considered necessary to establish a maximum acceptable concentration for chloramines in drinking water, based on the low toxicity of monochloramine at concentrations found in drinking water. Any measures taken to limit the concentration of chloramines or their by-products in drinking water supplies must not compromise the effectiveness of disinfection.”

Background: Chloramines are found in drinking water mainly as a result of treatment, either intentionally as a disinfectant in the distribution system, or unintentionally as a by-product of the chlorination of drinking water in the presence of natural ammonia. As monochloramine is more stable and provides longer-lasting disinfection than chlorine, it is commonly used in the distribution system as a secondary disinfectant.

Chlorine is more effective as a primary disinfectant and is used in the treatment plant.

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