The municipal water supply here is sourced from underground
aquifers and contains rather high concentrations of minerals such
as calcium and magnesium, i.e., the water is 'hard.'
Hard water is problematic in that it can form constrictive mineral
deposits inside plumbing, eventually resulting in reduced water
flow. Hard water also prevents soaps and detergents from lathering
properly, and it also leaves white, crusty deposits on dishes and
utensils that are allowed to air-dry after being washed.
A water softener works by passing the incoming hard water through a
tank containing a bed of special resins laced with sodium ions. As
the hard water flows through, some kind of chemical reaction takes
place which results in the sodium ions trading places with the
calcium and magnesium ions in the water. This 'softened' (and very
slightly salty) water then flows into the plumbing of the house for
general use.
As the sodium ions in the resin beds are depleted, the system loses
its ability to soften the water, and has to be 'regenerated.'
Regeneration is accomplished by pumping a highly concentrated brine
(salt) solution through the resin tank. This reverses the chemical
reaction used to soften the water, resulting in the accumulated
calcium and magnesium ions being flushed out, and the resin beds
being 'recharged' with a fresh supply of sodium ions.
The time between regenerations usually depends on the capacity of
the system; given the same amount of water consumption, a system
with a larger resin tank can go longer between regenerations. The
regeneration process itself takes several hours, and is usually
automatically scheduled to occur during periods of non-peak water
consumption, for example, in the early hours of the morning. Older
systems regenerate at fixed time intervals; newer ones, like mine,
regenerate based on water consumption.
The only recurring maintenance that has to be performed on a
typical household water softening system is to ensure that the
brine tank is kept filled with an adequate supply of salt. It's a
small price to pay, as a 50 lb. bag of water softening salt (really
just regular salt formed into conveniently-sized briquettes)
typically only costs around $5.
