Hard water is water that has high mineral content.
The simple definition of water hardness is the amount of dissolved calcium and magnesium in the water. Hard water is high in dissolved minerals, both calcium and magnesium.
General guidelines for classification of waters are: 0 to 60 mg/L (milligrams per liter) as calcium carbonate is classified as soft; 61 to 120 mg/L as moderately hard; 121 to 180 mg/L as hard; and more than 180 mg/L as very hard.
There are lots of examples of the way solubility of different substances affects our everyday life. With an increase in these minerals, the following are seen (1):
Soap scum in sinks and bathtubs
Bathtub rings
Spots on dishes or shower doors
Reduced foaming and cleaning abilities of soaps and detergents
Dingy and yellowed clothes with soapy residues that require extra rinsing to remove
Clogged pipes from buildup of minerals
Increased water heating costs from buildup of minerals, reducing efficiency of water heaters
Possible skin infections from bacteria trapped in pores underneath soap scum
Learn more about water hardness from sources below:
water.usgs.gov
extoxnet.orst.edu
www.water-research.net