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Health Products > Water Purifiers
Water Filtration & Purification - What system do you
need?
There are a wide
range of filters and purifiers available. You see
them in shopping malls and mail order catalogues.
The prices range from $50 to thousands of dollars.
What we all want to know is... which one do I need?
It is our hope that the following will help you to
understand what each system does and how much they
should cost. Please note that we do not sell filters.
Jug
Filters are a cheap and easy option that
give you a reasonable tasting water and remove some
contaminants.
They are generally a Granular Activated Carbon (GAC)
filter with a life of around 100 to 150 litres. Some
jug filters also incorporate de-ionising crystals,
but this effect will only last for a few jug fills.
Jug prices average about $30.00 and refill cartridges
are about $10.
Sediment
filters are used to screen out particles .
These systems are generally used on water supplies
that are visibly dirty or or have a risk of
cryptosporidium/ giardia. Commonly they are 50
microns, 20, 10, 5 and 1 m. There are 1000 microns to
a millimeter. The sediment filter is often combined
with or integrated into other types of filters. Such
filter will have a micron rating. Note that giardia
has a micron rating of 5, so a giardia safe filter
will need to have a rating of 1 micron.
Some sediment
filters are washable. This means that the diriment is
washed off giving the filter a longer life. This is
only practical for filters over 5 microns.
Granular
Activated Carbon (GAC) and Carbon Bock Filters
are primarily used to filter out chlorine, particles
(due to integral sediment screens) and bad taste.
This system will also remove organics, herbicides,
pesticides, some viruses and detergents. The granular
carbon filters usually have a micron rating of 25,
are now less popular since the advent of carbon block
cartridges. Carbon block cartridges let water flow
through faster and can have micron ratings as low as
one. Carbon filters are the most widely advertised.
KDF
Filters: are usually combined with carbon.
KDF has a brown metallic substance, that when water
passes through it, creates an electro-chemical
reaction. It crates a current of 0.4 volts that
should change chlorine into chloride etc, which is
less harmful and is easier to filter. KDF coupled
with carbon produces a filter with a longer life than
carbon alone. KDF will remove a small quantity of
some heavy metals.
Mixed Bed
Resin and De-Ionising Crystals: use ion
exchange particles to "filter" out heavy
metals. They are usually combined with carbon and
sediment filters so as to catch chlorine and
particulates as well. This system requires frequent
filter replacements to maintain optimum efficiency.
Distillers
work by evaporating water, leaving contaminants
behind, re-condensing it and collecting in a
container. This system results in very pure water
which is suitable for short cleansing diets and
topping up your car battery. Distillers remove approx
99.99% of total dissolved salts from the water.
Dissolved salts are very difficult to remove as they
are dispersed evenly in the water at a molecular
level. Fluoride exists as a dissolved salt. One
disadvantage however is that they also remove free
oxygen from the water as well resulting in a flat
oxegenless water (this is toxic to goldfish) Waste
flavour can be improved by using a carbon filter, and
distiller boiling trays need to be cleaned regularly.
Reverse
Osmosis is a system that requires water
pressure to work, (absolute minimum of 40 psi) Water
is forced though a very fine membrane, the mesh holes
are measured in angstroms, There are 10,000 angstroms
to a micron. Most gasses and some water will pass
through this membrane, but water contaminants will
not. The result is very pure bubbly water. Reverse
Osmosis will remove approx 98% of total dissolved
salts when new. One disadvantage is that that it
disposes of 4 times as much water as it purifies.
However for the average family home this amounts to
les than one washing machine cycle per week. or less
than 1% of total household waste water. Reverse
osmosis will also purify sea water fo drinking.
Filter Comparison Chart
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