NATIONAL SURVEY FOR CADMIUM, CHROMIUM, COPPER, LEAD, ZINC, CALCIUM, AND MAGNESIUM IN CANADIAN DRINKING-WATER SUPPLIES

A national survey was conducted to determine the levels of Cd, Cr, Cu, Pb, Zn, Ca, and Mg in Canadian drinking water supplies. Samples of raw, treated, and distributed water, obtained from 70 municipalities across Canada, were analyzed by atomic absorption spectrometry. The concentrations of trace metals found were essentially the same for all three types of water samples. The median and range values for distributed water expressed as ng of metal/mL of water were found to be: Cd ≤ 0.01 (≤0.01-0.49); Cr ≤ 2.0 (≤2.0-8.0); Cu, 20 (5.0-620); Pb ≤1.0 (≤1.0-65.0); Zn, 10 (≤5.0-380). Values for water hardness, expressed as mg of CaCO3/L, ranged from 1 in St. John's, Newfoundland, to 554 in Selkirk, Manitoba. Contamination of the water supplies with these metals except copper was minimal during treatment and distribution. In all cases, the median values for the distributed water were well below the WHO upper limit recommendations. © 1979, American Chemical Society. All rights reserved.