What Causes Hard Water in Wells?

Hard well water is caused by mineral contaminants found in groundwater.

Hard water is a common problem in well water that causes several problems if it is not dealt with. Hard well water is caused by the presence of minerals in the groundwater the well draws from. Calcium and magnesium are the two minerals most commonly responsible for hard water. While hard water does not present a health threat, it does cause pipe-clogging mineral buildups and interferes with the cleaning action of most soaps.

Causes

Hard well water is caused by the presence of dissolved minerals in the groundwater the well uses as a source. These minerals enter a well's groundwater from mineral sources in the soil and rock in and around the water table. As water moves through the soil, it dissolves trace amounts of these minerals and carries them with it. Although calcium and magnesium are the most common causes of hard water, the presence of iron, aluminum, barium, zinc, manganese or strontium also causes hard water.

Effects

Hard water consists of water that contains dissolved traces of calcium or magnesium. Over time, the minerals dissolved in hard water form deposits on the inside of pipes and pumping equipment resulting in reduced output and inefficient operation. Hard water also creates filmy, scaly deposits on metal or glass surfaces where it is used regularly. Well water that is used for washing will require larger quantities of soap to clean effectively and may leave a sticky film that inhibits cleaning and acts as a skin irritant.

Health Impact

Hard well water has no known negative health effects. According to the National Research Council, the calcium and magnesium dissolved in hard water provides a small amount of the dietary minerals required by the human body. The NRC also states that hard water can act as a major source of dietary minerals in water sources with high concentrations of these minerals.

Testing

Hard water testing kits are available for testing wells and other private water supplies. Test results that indicate water hardening minerals in concentrations between 17.1 and 60 parts per million indicate slightly hard water while concentrations of over 120 PPM are classified as hard.

Treatment

There are two basic options for treatment that include ion exchange and chemical water softening. Chemical water softeners use a liquid or powdered chemical --such as lime -- to alter the chemical composition of the water. This process often clouds treated water with calcium and magnesium precipitate. Ion exchange units use a filtering bed to replace hardness causing minerals with sodium. The filtering medium periodically requires recharging to continue working. This type of unit has the disadvantage of increasing the salt content of the water it treats.

References

• Neb Guide: Drinking Water: Hard Water (Calcium and Magnesium); Sharon O. Skipton, et al; July 2009
• National Drinking Water Clearinghouse: Lime Softening; June 1998
• UK Cooperative Extension Service: Drinking Water Contaminant - Hard Water; December, 2010
• Water-research.net: Hard Water Hardness Calcium Magnesium Water Corrosion Mineral Scale
• Kentucky Geological Survey: Frequently Asked Questions About Groundwater and Water Wells in Kentucky