The life of refrigerator water filters is dependent upon the volume of
contaminants in the water as well as the amount of use of the filter. Well water
is more likely to contain contaminants not found in publicly treated water and
may need more frequent filter changes. As a rule of thumb, the filter should be
changed as specified by the manufacturer or at least every six months.
Carbon is the primary substance used in water filtration methods because
carbon has the potential to absorb many of the chemicals found in water. Most
refrigerator water filters, which meet NSF/ANSI 42 certification standards, use
granular activated carbon (GAC) to attract chemicals and impurities responsible
for bad taste and odor, such as those that are a by-product of chlorine. These
filters are not capable, however, to rid water of more dangerous,
health-threatening contaminants. The method by which water is channeled through
GAC filters does not allow sufficient time to complete the absorption of such
substances. Various bacteria are formed, trapped and allowed to multiply, which
further contaminates water processed by the filters. Carbon is not capable to
absorb heavy metals, such as lead. GAC filters may trap some heavy metals and
sediments, but allow others to filter through to the output water. Failure to
change the water filter, every six months, allows unabsorbed water contaminants
and newly formed bacteria to saturate the filter, forcing the filter to leak
contaminants back into processed water. The water output may contain more
contaminants than the filter was intended to remove in the first place.
Technology has lead to the development of more absorbent carbon-based
filters, solid carbon block filters. These filters include solid blocks of
carbon to absorb contaminants from water. Water takes longer to strain through
carbon blocks than it does carbon granules, so that carbon blocks provide
sufficient time for the absorption of more health-threatening containments.
While carbon block filters are capable to absorb toxics, pesticides, TTHMs and
other contaminants, they cannot absorb heavy metals or contaminants that are
by-products of agricultural fertilization, such as nitrates or sulfides. The
composition of carbon blocks allows them to restrain heavy metals and bacteria
away from output water, however, nitrates and sulfides are not filtered. Even
so, carbon block filters are sufficient to meet NSF/ANSI 53 certification
standards. Failure to change carbon block filters, every six months, allows
contaminants to saturate the filter, forcing the filter to leak contaminants
into the processed water. When sediments are not removed from water, those
sediments buildup and corrode filter fittings and water fixtures, causing them
to leak. This type of damage to filters and fixtures may cause the output water
to contain more contaminants than the water input to the filter. Failure to
change the filters might also reduce the water pressure, within the filtering
system, forcing it to be ineffective.
Some refrigerator water filters may include fiber water filters. These
filters are made of tightly wrapped fibers of rayon or spun cellulose, which
trap rust, lead and other sediments found in water. When used alone, these
filters are ineffective in reducing any chemical or health-threatening
contaminants. Fiber filters are best suited for use with other types of filters
to reduce the concentration of sediments. They should be replaced, every six
months, to avoid a build-up of sediments that would force the filter to leak the
contaminants back into the processed water.
