Water Softeners

Water softeners remove the hardness minerals calcium and magnesium. Water exceeding about 7 to 8 grains per gallon hardness may interfere with the cleaning action of soaps and detergents, and cause scale buildup in hot water pipes, water heaters, and plumbing fixtures.

The most common way to soften household water is to use a cation exchange water softener. A synthetic resin with a strong attraction for calcium, magnesium, and other positively charged metal ions (cations) is first saturated with sodium cations from a salt (sodium chloride) solution. As the water passes through the resin, the sodium exchanges with calcium and magnesium.

Softeners are automatic, semi-automatic, or manual depending on the system for regeneration of the resin. Each type is available in several sizes and is rated on the amount of hardness it can remove before regeneration is necessary.

Limitations
Individuals on a sodium-restricted diet should consult a physician before using softened water. A possible solution is to have drinking and cooking water lines bypass the water softener. Water softening units also remove small amounts of iron. However, using a softener to remove iron in naturally soft water is not advised. Refer to the iron filter section of this publication.

Maintenance
When the resin is filled to capacity with calcium and magnesium, it must be recharged. Fully automatic softeners regenerate on a preset schedule and return to service automatically. Regeneration is usually started by a time clock, although some units start regeneration by water-use meters or hardness detectors.

Semi-automatic softeners have automatic controls for everything except for the start of regeneration. Manual units require manual operation of one or more valves to control backwashing, brining, and rinsing.

In many areas, there are companies that provide a water softening service. For a monthly fee,the company installs a softener unit and replaces it periodically with a freshly charged unit. The replacement schedule depends on the water hardness and the amount of water used.