What is 'hard water?'

Water is a solvent and dissolves minerals it contacts as it moves through rock and soil. Compounds of calcium and magnesium are the minerals that most commonly make water "hard," though other metals may contribute. Minerals that are in solution at room temperature tend to solidify when heated, forming scale on equipment.

Hard water also requires more soap and synthetic detergents.

Harness is measured in grains (per gallon) or parts-per-million (ppm) — 1 grain = approx. 17ppm.

Water with harness greater than 5 grains is considered for treatment; 10 grains and above will appreciably shorten the life of water heaters, boilers, electric heating elements and other water-using appliances.