Water hardness is a term that describes the amount of minerals, such as magnesium and calcium, contained in a water source. When these minerals appear in relatively high concentrations, they can cause cosmetic or physical damage to household or municipal supply lines and equipment. Water utilities analyze hardness levels by measuring mineral grains per gallon of water or milligrams of minerals per liter of water.
The Basics
Hard water is created when water passes through rock or soil, dissolving minerals contained in these materials, according to the Fairfax, Virginia, County Water Authority. In addition to hard water's effects on your household containers and appliances, the U.S. Geological Survey lists potential consequences of water hardness, including scaling in boilers and other industrial equipment, as well as a need for increased amounts of soaps and detergents to adequately clean clothes and dishes. The highest concentrations of hard water in the U.S. occur in an area that includes the Great Plains and southern California.
Hardness Analysis
If laboratory analysis shows a mineral content of less than one grain per gallon, or less than 17.1 mg/L, your water is classified as soft, the Fairfax County Water Authority reports. You have slightly hard water if it contains mineral concentrations between 1.0 and 3.5 grains per gallon, or between 17.1 and 60 mg/L. You have moderately hard water if it contains mineral concentrations between 3.5 and 7.0 grains per gallon or between 60 and 120 mg/L. You have hard water if it contains concentrations between 7.0 and 10.5 grains per gallon or 120 and 180 mg/L. Very hard water contains mineral concentrations above 10.5 grains per gallon or above 180 mg/L.
Risks
Hard water does not pose a threat to human health, according to Washington University in St. Louis, and the U.S. Environmental Protection Agency does not maintain water hardness standards. Still, high mineral content in water can trigger the formation of unsightly scale in cooking utensils, restrict normal flow in your water lines and decrease the effective lifespan of your water pipes and appliances. In addition, reduced efficiency from water hardness can ultimately contribute to increases in your utility costs.
Reducing Hardness
To reduce the mineral content of your water supply, your local provider may add a combination of soda ash and slaked lime, Washington University in St. Louis reports. These substances alter the chemical structure of calcium and magnesium, rendering them susceptible to separation and removal. You may also use a water softening process to treat hard water in your home. Typically, these processes involve the use of ion exchange devices that replace magnesium and calcium ions in your water with non-hardening sodium ions.
Considerations
In some cases, hard water can contribute to your total dietary intake of magnesium and calcium, according to the National Research Council and the World Health Organization. This may be significant, since substantial numbers of people in most countries do not get adequate amounts of either or both of these minerals in their daily diets.
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