The term, ""hard water,"" refers to water with a high mineral content. The most common minerals that cause water hardness are calcium and magnesium. As water is absorbed into the ground, the minerals are pulled from the earth and eventually end up in a household's water supply. Hard water can clog household plumbing.

Water hardness, or how much of a mineral is present in water, is measured in grains per gallon (GPG), parts per million (PPM), or milligrams per liter (MG/L). Water up to 1 GPG is considered soft, water; from 1 to 3.5 GPG is considered moderate, and water 3.5 to 7 GPG is hard water. Kits used to test water hardness can be purchased at a pool supplier or from a water softener dealer.

Many water softeners plug right into the household water supply. Ionic exchange water softeners consist of negatively charged plastic beads, a brine tank, and a regenerating system with a timer or other monitoring device. Sodium or potassium chloride is added to the brine tank when regeneration is necessary. Home water softeners range in price from $400 to $1,200, and the salt ranges from $5 to $7 per bag. Price depends on type, size, and type of softening agent. Alternatively, magnetic water softeners consist of only 2 magnets attached to the outside or inside of water pipes.

Water softeners work by replacing ions of the minerals that cause hardness with "softer" ions. Water is filtered through charged plastic beads and the magnesium or calcium ions are replaced with sodium or potassium ions. In the case of magnetic water softeners, magnetic energy causes chemical changes in the minerals.

Using water softeners poses no health risks, except for those who are on sodium-restricted diets. Keep bottled water on hand for cooking and consumption, or use potassium chloride instead of sodium chloride to soften. Potassium chloride is more expensive than sodium chloride. There are also no health risks associated with choosing not to soften water.