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Water Softeners

Hard water is caused by dissolved calcium and magnesium in the water. Hard water interferes with laundering, washing dishes, and bathing. It also effects appliances. For example scale builds up in water heaters, increasing the costs of heating water and reducing the life of the appliance. Hard water used with soap causes soap deposits that will not dissolve or remove easily.

Water is softened by passing it through a bed of ion-exchange resin. The softening process exchanges calcium and magnesium ions in the water for sodium ions in the resin. Approx. 15 mg of sodium is added per gallon for each grain of hardness reduced. When the sodium is exhausted, the softener needs to be regenerated. This is done by backwashing to clean the ion-exchange material, bring with salt (sodium chloride) to replace sodium ions, and rinsing to remove any excess salt. There are three types of ion-exchange softeners for the home:

Manual Water Softeners
Each step for recharging the unit must be activated by hand. Salt needs to be added each time directly to the single tank of the softener.
Semi-Automatic Water Softeners
The homeowner sets the system switches when recharging is necessary. The system completes the process without need for further attention. A second tank is required for the salt solution.
Automatic Water Softeners
All steps of the recharging process are controlled by a timing mechanism that the homeowner sets based on water usage. Some models even measure water usage and recharge themselves when needed. Brine is stored in a second tank.

The increased sodium in the softened water is a concern of individuals on a sodium-restricted diet. In such a case the drinking water is bypassed from the softener. The cost of the water softener is balanced against the savings of soft water. Using soft water reduces the quantity of soaps and detergents needed by as much as 50%. The lives of the water using home appliances and the plumbing system are extended.

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