Drinking water right out of the tap is becoming less common these days.
Typically, Americans get their water from a bottle, from a filtered pitcher
or from a filtering device connected to the tap. Selecting the best water
filter for your needs is a much easier process when you understand the
options that exist. Keep in mind that water filtering is not to be confused
with home water treatment. Water treatment is a broader category, including
filters, but also distilling and water softening systems. Filtering devices
are generally used for drinking water, while these larger systems are
employed throughout the home for water that leaves any tap.
Three kinds of filtering devices are available: carbon filters, fiber
filters and filters that use reverse osmosis. Carbon filters are, by far,
the most common, followed by fiber filters, and then the more expensive
reverse osmosis unit. Advantages exist with each filter-choosing the one
the works best for your needs is the best way to select a filter.
Carbon filtering devices use carbon cartridges with a porous surface. The
cartridge absorbs a variety of substances, odors and disagreeable tastes.
The effectiveness of this filter depends on the amount of carbon in the
unit, and how long water stays in the filtering unit. The carbon has more
time to remove impurities the longer the water is in contact with it.
Filters that contain a large volume of charcoal generally remove more
organic material at the beginning of the cartridge life, and have a better
performance over time than those filters with smaller amounts of charcoal.
Faucet-mounted filters attach to a faucet once the aerator is removed.
There are two basic designs. One uses a by-pass valve that filters only
water for cooking and drinking. The second design has no by-pass valve, so
all water flowing through the faucet is filtered. Some models sit on a
counter and have a hose running from the faucet to a charcoal filter, while
others are permanently attached to the faucet. Special filter devices that
attach to ice makers can also be installed on the cold water supply line.
Fiber filters contain spun cellulose or rayon that trap sediment suspended
in water, also called turbidity. The tightly wrapped fibers form a cylinder
around a tubular opening. The pressure of the water line forces water
through the wrappings to the inner opening that leads to the faucet. The
fibers trap silt. Filtered water passes to the opening that leads to the
Reverse osmosis units use a membrane that actually separates water from
impurities. It does this by forcing water through a specially constructed,
semi-permeable, nonporous synthetic membrane that separates soluble and
suspended particles from the water. The process removes a wide variety of
substances from the water. More than 75 percent of minerals (like sodium,
calcium and chloride) may be removed from the water. Reverse osmosis has
also been reported to be effective in removing nitrate, fluoride and some
forms of arsenic. A membrane may last about one year, depends on quality of
water entering the unit. Reverse osmosis units should be installed by a
plumber, and are more expensive than other methods due to the complexity of
the operating system.
With some investigation on the Internet or in consumer magazines you can
easily learn about specific brands of filters for whichever type of filter
will work best for you.
Sources: The Los Angeles Daily News and Marilyn W. Caselman, Department of
Environmental Design, University of Missouri-Columbia