The net health hazard of drinking Toronto tap water is not easy to quantify and, considering the other dangers of modern life, may not seem worth worrying about. Daily toxin ingested in food may be five to ten times the toxin intake from water. Softening water may offer some advantages, but probably no health advantage. Hard water causes spotting on glassware, rings in bathtubs and dingy films on clothes. The fact that calcium and magnesium precipitates soap means that more soap is needed for all washing.
Hard water can also clog plumbing and make water taste bad.
Not only are calcium and magnesium protective of the cardiovascular system, but soft water causes more lead and cadmium to leach out of pipes. Water softening devices typically use ion-exchange resins to replace calcium and magnesium with sodium, which can raise blood pressure. Some brands of bottled water studied by the Toronto Public Health authorities had less aluminum, lead and nickel than tap water, but more barium and cadmium. Glass bottles can release heavy metals into water. Distillers accumulate hard residues, primarily composed of calcium and magnesium.