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It is not considered necessary to establish a guideline for chlorine in drinking water, based on its low toxicity at concentrations found in drinking water as a result of treatment. Any measures taken to limit the concentration of chlorine or its by-products in drinking water supplies must not compromise the effectiveness of disinfection.

The maximum acceptable concentration (MAC) for chlorite in drinking water is 1 mg/L. The MAC for chlorate in drinking water is 1 mg/L. A guideline for chlorine dioxide is not required because of its rapid reduction to chlorite in drinking water. Utilities should make every effort to meet the guidelines, however, any method of control employed must not compromise the effectiveness of water disinfection.

The production of ammonia is a normal part of metabolism, and levels occurring in the human body from metabolic processes generally exceed concentrations found in drinking water. The concentration of free ammonia entering the distribution system can lead to nitrification and the potential increase of nitrate and nitrite in drinking water. This guideline technical document reviews and assesses all identified health risks associated with ammonia in drinking water.

There is no consistent, convincing evidence that ingested asbestos is hazardous. There is, therefore, no need to establish a maximum acceptable concentration (MAC) for asbestos in drinking water.

The guideline technical document for trihalomethanes (THMs) also includes a specific guideline for bromodichloromethane (BDCM). The maximum acceptable concentration (MAC) for trihalomethanes (THMs) in drinking water is 0.100 mg/L (100 µg/L) based on a locational running annual average of a minimum of quarterly samples taken at the point in the distribution system with the highest potential THM levels. The maximum acceptable concentration (MAC) for bromodichloromethane (BDCM) in drinking water is 0.016 mg/L (16 µg/L) monitored at the point in the distribution system with the highest potential THM levels.

Low levels of fluoride occur naturally in most sources of drinking water in Canada. Fluoride can occur naturally in surface waters from the deposition of particulates from the atmosphere and the weathering of fluoride-containing rocks and soils, and in groundwater from leaching from rock formations. The maximum acceptable concentration (MAC) for fluoride in drinking water is 1.5 mg/L.

Although benzene is naturally occurring at low concentrations, its presence in the environment is mostly related to human activities. Gasoline contains low concentrations of benzene (below 1%), and emissions from vehicles are the main source of benzene in the environment. Benzene can be introduced into water by industrial effluents and atmospheric pollution. This Guideline Technical Document reviews and assesses all identified health risks associated with benzene in drinking water.

Health Canada has developed a guideline value for chloramines in drinking water to protect the health of Canadians. Learn about what it means to have chloramines in your drinking water.

Because cyanide is toxic to humans, a maximum acceptable concentration of 0.2 mg/L (200 µg/L) for free cyanide in drinking water has been set.

An aesthetic objective of ≤250 mg/L has been established for chloride in drinking water. At concentrations above the aesthetic objective, chloride imparts undesirable tastes to water and to beverages prepared from water and may cause corrosion in the distribution system.