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Nitrate and nitrite are widespread in the environment. They are naturally produced by the oxidation of nitrogen by microorganisms and, to a lesser extent, by lightning. The maximum acceptable concentration (MAC) for nitrate in drinking water is 45 mg/L. This is equivalent to 10 mg/L measured as nitrate-nitrogen.

Mercury is a toxic element and serves no beneficial physiological function in man; a maximum acceptable concentration of 0.001 mg/L (1 µg/L) in drinking water has therefore been established.

Boron is an essential element for plant growth and is applied directly to the soil as a plant fertilizer. Sodium borate and boric acid are used as fungistatic agents on vegetables, fruits and trees. The maximum acceptable concentration (MAC) for boron in drinking water is 5 mg/L (5000 µg/L).

Although hardness may have significant aesthetic effects, a maximum acceptable level has not been established because public acceptance of hardness may vary considerably according to the local conditions. Water supplies with a hardness greater than 200 mg/L are considered poor but have been tolerated by consumers; those in excess of 500 mg/L are unacceptable for most domestic purposes.

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.

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.

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.

Dicamba is a broad-spectrum chlorobenzoic acid herbicide used in large quantities for general weed control on grain crops, pastures and non-crop areas. The maximum acceptable concentration (MAC) for dicamba in drinking water is 0.12 mg/L (120 µg/L).

Naturally occurring barium can be found in most types of rocks and can enter surface and groundwater by leaching and eroding from sedimentary rocks. A maximum acceptable concentration (MAC) for total barium in drinking water is 2.0 mg/L (2,000 µg/L).

Atrazine is used extensively in Canada as a pre- and post-emergence weed control agent, primarily for corn but also for rapeseed, and for total vegetation control in non-cropland and industrial areas. The maximum acceptable concentration (MAC) for atrazine in drinking water is 0.005 mg/L (5 µg/L).