How Water Softener Works

The idea behind a water softener is simple: the calcium and magnesium ions in hard water are replaced with sodium ions. Learn more about the harmful effects of hard water -- and the benefits of soft water -- in this HowStuffWorks podcast.

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Episode Transcript

Speaker 1 (00:00):
Welcome to brain Stuff from how stuff works dot com
where smart Happens. Hi, I'm Marshall Brain with today's question,
how does a water softener work? We call water hard
if it contains a lot of calcium or magnesium dissolved
in it. Hard water causes two problems. First, it can
cause scale to form inside of pipes and water heaters

(00:24):
and tea kettles. The calcium magnesium participate out of the
water and stick to things. Eventually pipes can become completely clogged. Second,
the calcium and magnesium react with soap to form a
sticky scum and also reduces the soaps ability to lather.
Since most of us like to wash with soap, hard
water makes a bath or a shower less productive. The

(00:46):
solution to hard water is either to filter the water
by distillation or reverse osmosis to remove the calcium and
magnesium altogether, or to use a water softener. Filtration would
be expensive to use or all the water in a house,
so a water softener is usually the less expensive solution.
The idea behind a water softener is simple. The calcium

(01:09):
and magnesium ions in the water are replaced with sodium ions.
Since sodium does not precipitate out in pipes or react
badly with soap. Both the problems of hard water are
completely eliminated. To do the ion replacement, the water in
the house runs through a bed of small plastic beads
or through a chemical matrix called zeolite. The beads or

(01:32):
zeolite are covered with sodium ions. As the water flows
past the sodium ions, they swap places with the calcium
and magnesium ions. Eventually the beads or zeolite contain nothing
but calcium and magnesium and no sodium, and at this
point they stop softening the water. It's then time to
regenerate the beads or zeolite. Regeneration involves soaking the beads

(01:57):
or zeolite in a stream of sodium ions. Salt is
sodium chloride, so the water softener mixes up a very
strong Brian solution and flushes it through the zolder beads.
This is why you load up a water soften or
with salt crystals. The strong Brian displaces all the calcium
and magnesium that is built up on the beads and

(02:18):
replaces it again with sodium. The remaining Brian plus all
the calcium and magnesium is flushed out through a drain pipe.
Regeneration can create a lot of salty water, something like
twenty five gallons for each cycle. Do you have any
ideas or suggestions for this podcast? If so, please send
me an email at podcast at how stuff works dot com.

(02:42):
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