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Water conditioning is a major market for salt.
Hard water–water containing excessive calcium and magnesium–is a problem ( 1 2 3 4 5 6 7 ) recognized in many parts of North America and Europe. As a result, water softening systems have become popular, even deemed a necessity in industrial installations, institutions and private homes.
As it leaves the skies in the form of rain, water is soft, meaning it is clear of impurities. But is picks up carbon dioxide and other impurities in the air. It also dissolves calcium and magnesium salts as it soaks through the earth and runs off into rivers or lakes and collects in reservoirs or wells. If in these processes it picks up a substantial amount of calcium carbonate and other substances, it becomes "hard." This water leaves mineral deposits which clog plumbing equipment and appliances making it unsatisfactory for household or industrial uses. In particular, hard water destroys the efficiency of industrial boilers. Most notably in the home, hard water inhibits proper sudsing of soaps, shampoos and detergents.
Most water softening systems pass the water through a bed of special resins, which can exchange sodium ions for the "hard" calcium and magnesium ions in the water. Eventually, the resin exhausts its sodium and must be "recharged." This is done by running salt brine, containing sodium, through the resin bed, removing the calcium and magnesium ions from the bed and leaving a new supply of sodium. The brine is produced by the addition of salt to the water softener. The calcium, magnesium and any excess salt is discharged. Sodium ions are added to softened water; less than 8 mg per liter per grain of hardness. Many websites discuss how ion-exchange water conditioners work ( 1 2 3 4 5 6 7 8 )
Many industries require softened water for such uses as processing and dyeing textiles, tanning leather, cleaning dairy equipment and commercial laundering. Water softening systems are installed in some municipal water systems for the dual purpose of protecting the plant equipment and better serving industrial and residential users. But the greatest use of water softeners is in homes. People have come to expect quality in their water as well as in other things in their lives.
The Salt Institute has produced a summary of the benefits of water softening that many water treatment dealers find useful in answering questions which arise during sales presentations. If you are looking for information about the quality of salt for water softener use, these two articles will be helpful ( 1 2 ).
Half of all new homes built in the U.S. use onsite wastewater (septic) disposal systems and 30 million U.S. homes have septic systems. Allegations that water softener discharges to these systems impede their efficient operation have been thoroughly refuted ( 1 2 ). In fact, a symposium was conducted in October 2005, sponsored by the National Onsite Wastewater Recycling Association; summaries and the major paper are available online from Water Conditioning & Purification magazine ( 1 2 )
For further information contact the Salt Institute, the Water Quality Association, the American Water Works Association, the Water Quality and Health Council, salt companies like Morton Salt, Cargill Salt and Sifto Canada, water treatment companies Culligan and Eco Water, or three water treatment industry trade publications, Water Conditioning & Purification (see the WC&P review of our website), Water Technology/WT Online and Agua Latinoamerica. Note our disclaimer.
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