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Filtration
Filter systems are a relatively simple and effective way to control a variety
of contaminants. These include mechanical filters, activated
carbon filters, oxidizing filters and neutralizing
filters. Filtration systems are designed for use only on potable water.
This means that your water supply should be clean, uncontaminated and suitable
for drinking.
Mechanical filters (microfiltration)
Mechanical filters remove suspended material from water,
including sand, silt, clay and organic matter. They do not remove dissolved
or very fine particles and are often used in combination with other treatment
equipment. Filters are commonly of fabric, fiber, ceramic or other screening
material. Mechanical filters
can be cartridge units, mounted in a single waterline or on a tap, or tank units,
which treat an entire household water supply. The filters must be serviced periodically.
Activated Carbon Filters
Activated carbon filters absorb impurities as they pass through
a carbon cartridge. Generally, they are used to eliminate undesirable odors
and tastes, organic compounds and to remove residual chlorine. Some units such as the whirlpool water filters are easy to install and maintain. Most inorganic
chemicals, metals, microorganisms and nitrates are not removed by the filters.
Carbon filters also remove some
potentially hazardous contaminants such as radon gas, many dissolved organic
chemicals and trihalomethanes. If low levels of these contaminants exist, a
whole-house unit can be used. However, these filters are not designed to remove
persistently high levels of these contaminants. When contamination cannot be
eliminated, an alternative water supply may be the safest solution.
Oxidizing filters
Oxidizing filters remove iron, manganese and hydrogen sulfide
(rotten egg odor). A manganese zeolite-coated filter causes dissolved iron and
manganese to form particles the filter then traps. These filters are useful
in removing iron if a water softener is not wanted. The filter usually treats
the entire household water supply. Periodically, the filter must be rinsed with
a chemical solution to remove the accumulated iron and manganese.
Neutralizing filters
Neutralizing filters treat acidic water. The filter treats
all of the home water supply by passing it through limestone chips or other
neutralizing agent. Where acidic water does occur, it can leach lead, copper
or other toxic metals from household pipes into the water supply.
Two potential problems occur with the filter. First, it may increase water
hardness. Secondly, acidic water may intensify any iron problems already present
in the water supply. The filter requires little maintenance except the need
to occasionally replace the limestone chips.
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