Water Softener
System
Calcium and magnesium cause hard
water, and high levels can precipitate and clog pipes. The best way to
soften water in household water systems is to use a water softener
unit connected into the water supply line. You may want to consider
installing a separate faucet for un-softened water for drinking and
cooking. Water softening units also remove iron.
Water Softener
General Description
The most common way to soften
household water is to use a cation-exchange water softener. Softeners
may also be safely used to remove up to about 5 milligrams per liter
of dissolved iron if the water softener is rated for that amount of
iron removal. |
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Water Softener
System Limitations
Using a softener to remove iron in
naturally soft water is not advised; a green-sand filter is a better
method.
Maintenance
When the resin is filled to capacity, 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; some units are started by water use meters or hardness
detectors.
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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 periodicallywith a freshly charged unit.
Need for Iron Removal
Iron in the ferric form and manganese will stain clothes and plumbing
fixtures. Ferrous iron is in the dissolved form and cannot be seen in
water. When water containing ferrous iron is exposed to air, the iron
oxidizes and ferric iron is formed. Ferric iron usually appears as
rust colored particles floating in the water.
Water with a high iron or manganese content is not considered a health
problem, but it can be very objectionable in taste, odor or
appearance. Iron bacteria are nuisance organisms often associated with
soluble iron in water. Because they cause a slime buildup they
can be quite objectionable. Calcium is an essential nutrient for this
bacteria. The presence of iron bacteria is indicated by a gelatinous
slime on the inside wall of the toilet flush tank and gelatinous
"rusty slugs" being discharged at the tap. High dosages (200 to
500 milligrams per liter) of chlorine (known as shock chlorination or
disinfection) are required to control iron bacteria.
Shock chlorination must include the well and system.
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Four types of iron-removal equipment are available:
Iron Filters. Iron filters are only useful for removal of ferrous
iron and manganese; ferric iron will plug them. They appear similar to
water softeners but contains a bed of natural or synthetic manganese
green sand. Manganese dioxide oxidizes iron and manganese and the
oxidized particles are then filtered out in the lower part of the bed.
Water softeners. All water softeners will remove iron; the
rating for iron depends on whether the regeneration will remove the
iron from the zeolite or not. Water softeners contain a zeolite
mineral that will remove soluble iron on an ion-exchange basis
(the same way calcium and magnesium are removed in water softening).
The slime produced by iron bacteria will clog the zeolite and reduce
its effectiveness.
Polyphosphate feeders. These units contain a phosphate compound
which coats the soluble iron and prevents its oxidation when the water
is exposed to air. The compound is not effective against iron that has
already oxidized.
When some waters are heated, the raised temperature will reduce the
effectiveness of the polyphosphate so that oxidized iron will
accumulate in the water heater. (Polyphosphate is only effective in
cold water. Heating the water will release the iron.) The heated
water will be rusty and unsatisfactory for home uses.
Chlorination and filter. Chlorination followed by filtration
through a sand filter can remove any quantity of iron in any form. The
chlorine oxidizes and precipitates the iron and the filter strains out
the particles. Carbon filtration may be required to remove excess
chlorine residue.
This method also destroys iron bacteria. When the bacteria cannot be
permanently eliminated by shock chlorination, continuous chlorination
is required. Known brands of
Water Softener Systems are: Culligan Water Softener and Kinetico
Water Softener.
Neutralizers
Primary Use This system treats corrosive (acidic) water.
Alkalinity and pH are increased through processing.
Passing the water through granular calcite (marble, calcium carbonate
or lime) is the most common method of home treatment. A mix of calcite
and magnesium oxide also is used. if the water is very acidic or if a
high flow rate is needed, a system to chemically feed soda ash, sodium
carbonate or caustic soda (sodium hydroxide) may be necessary. These
systems increase the sodium content of water, whereas using calcite or
lime increases calcium.
Disinfection Methods
Chlorination - Both municipal systems and households can disinfect
water by adding chlorine. Household systems commonly use household
bleach. Chlorination does not remove nitrates or other chemicals, but
may oxidize organics and some minerals such as iron. Chemical metering
devices must be maintained carefully. Using a carbon filter after
chlorination will remove any
excess chlorine and chlorinated chemicals that form.
Other Methods
Other methods of disinfecting water include boiling, pasteurizing,
treating with ultraviolet light, and treating with ozone. These
methods are usually less practical than chlorination or not readily
available. Note that sterilization (boiling water vigorously for at
least two minutes) kills all organisms. Disinfection reduces the
concentration of organisms to safe levels. Devices to kill or remove
bacteria or viruses are termed purifiers. Chlorination, distillation,
or boiling for 15 minutes are the usual methods used to purify water
for household use.
Disinfection by ozonation or ultraviolet light methods are replacing
chlorination in some water treatment plants, but are not yet readily
available for home use.
Some filtration units with silver-coated activated charcoal blocks are
being sold for removal or killing of bacteria. Before purchasing such
a unit, evaluate it carefully and check for sufficient test data and
certification to assure its effectiveness.
This information comes from North
Dakota State University
Extension bulletin E-430, Household Water Treatment.
Health risks
associated with softened water
During the softening process sodium is released from the
exchange media into the output water. For every grain of hardness
removed from water, 8 mg/1 (ppm) of sodium is added. People on
restricted sodium intake diets should account for increased levels of
sodium in softened water. Your family physician should be consulted.
Sodium intake from softened water can be avoided by leaving one
kitchen tap un-softened for drinking and cooking.
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