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WATER SOFTENERS
They make hard water easy to get along with.
An Overview By: THOMAS KLENCK, PM
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Water passing through the mineral
tank loses positively charged calcium and magnesium ions to negatively
charged plastic beads. The brine tank holds a salt solution that flushes
the mineral tank, replacing calcium and magnesium ions with sodium. A
meter at the top of the mineral tank regulates recharging cycles. The
valve assembly routes water flow for each phase of the regeneration
cycle. |
It's easy to forget how important water is in our lives. Of course we
need it in our diet, but in our homes, it's a tool-a fluid medium that carries
material from one place to the next. And one of the reasons it does this job
well is that it's very good at holding things, either by suspending them or
dissolving them.
Unlike most tools, though, water doesn't come with an
instruction manual. If it did, you'd know why the dishes you thought were washed
are covered with spots when dry, why the water in your shower leaves a film on
everything it touches, and why what you thought was clean water has clogged up
your plumbing system.
The Solution Is The Problem
While water is in the ground, it picks up soluble bits of whatever it passes
through. While this can mean contamination that makes the water unfit to drink,
in many cases it simply means that the water contains minerals found in the
earth. Of these, calcium and magnesium are of particular importance because they
affect the water's ability to function in our homes. These minerals make our
water hard.
One effect of hard water is that soaps and detergents
lose some effectiveness. Instead of dissolving completely, soap combines with
the minerals to form a coagulated soap curd. Because less soap is dissolved,
more is required. And the sticky insoluble curd hangs around-it clings to the
skin and may actually inhibit cleansing. Washed hair seems dull and lifeless.
In the laundry, things aren't much better. The soap curd
can work its way into your clothes as they're being washed in your automatic
washing machine. This can keep dirt trapped in the fibers, and it can stiffen
and roughen the fabric.
In addition to affecting the actual washing process,
insoluble soap deposits leave spots on everything you wash-from your dishes to
the family car-and a soap film will build up in your bath and shower.
Another reason to be concerned about hard water is its
effect on your plumbing system. Calcium and magnesium deposits can build up in
pipes, reducing flow to taps and appliances. In water heaters, these minerals
generate a scale buildup that reduces the efficiency and life of the heater.
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1. The backwash phase removes
dirt from the mineral tank. 2. Recharging the mineral tank with sodium
from the brine solution displaces calcium and magnesium, which is then
washed down the drain. 3. The final phase rinses the mineral tank with
fresh water and loads the brine tank so it's ready for the next cycle. |
The Fix
The solution to the problem is to get rid of the calcium and magnesium. While
there are chemical treatments that do this, the most popular answer is a water
softener.
The typical water softener is a mechanical appliance
that's plumbed into your home's water supply system. All water softeners use the
same operating principle: They trade the minerals for something else, in most
cases sodium. The process is called ion exchange.
The heart of a water softener is a mineral tank. It's
filled with small polystyrene beads, also known as resin or zeolite. The beads
carry a negative charge.
Calcium and magnesium in water both carry positive
charges. This means that these minerals will cling to the beads as the hard
water passes through the mineral tank. Sodium ions also have positive charges,
albeit not as strong as the charge on the calcium and magnesium. When a very
strong brine solution is flushed through a tank that has beads already saturated
with calcium and magnesium, the sheer volume of the sodium ions is enough to
drive the calcium and magnesium ions off the beads. Water softeners have a
separate brine tank that uses common salt to create this brine solution.
In normal operation, hard water moves into the mineral
tank and the calcium and magnesium ions move to the beads, replacing sodium
ions. The sodium ions go into the water. Once the beads are saturated with
calcium and magnesium, the unit enters a 3-phase regenerating cycle. First, the
backwash phase reverses water flow to flush dirt out of the tank. In the
recharge phase, the concentrated sodium-rich salt solution is carried from the
brine tank through the mineral tank. The sodium collects on the beads, replacing
the calcium and magnesium, which go down the drain. Once this phase is over, the
mineral tank is flushed of excess brine and the brine tank is refilled.
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In ion exchange, hard water ions
replace sodium ions on beads. Process is reversed to flush minerals
away. |
The Brains
Most popular water softeners have an automatic regenerating system. The most
basic type has an electric timer that flushes and recharges the system on a
regular schedule. During recharging, soft water is not available.
A second type of control uses a computer that watches
how much water is used. When enough water has passed through the mineral tank to
have depleted the beads of sodium, the computer triggers regeneration. These
softeners often have reserve resin capacity, so that some soft water will be
available during recharging.
A third type of control uses a mechanical water meter to
measure water usage and initiate recharging. The advantage of this system is
that no electrical components are required and the mineral tank is only
recharged when necessary. When it is equipped with two mineral tanks, softened
water is always available, even when the unit is recharging.
Judging Water Hardness
Companies that sell water softening equipment generally offer test kits that
help you determine the hardness of your water. For commercial testing sources,
check your Yellow Pages under "water analysis."
Water hardness is measured in grains per gallon (GPG) or
milligrams per liter (mg/l, equivalent to parts per million, or ppm). Water up
to 1 GPG (or 17.1 mg/l) is considered soft, and water from 1 to 3.5 GPG is considered moderately hard. Water from 3.5 to 7 GPG is Hard Water, and from 7 to 10.5 GPG is Very Hard. A water softener's
effectiveness depends on how hard the incoming water is. Water over
100 GPG may not be completely softened.
Health Concerns
Hard water poses no health hazard. On the other hand, the sodium that remains in
softened water may be a problem for those on sodium-restricted diets. Other
people simply may wish to avoid the slightly salty taste of treated water. In
either case you can install a separate water dispenser that bypasses the
softener. You also can use potassium chloride instead of salt, although this
costs about three to four times more.
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