Look for color change in the cartridge, reduced water flow or return of bad taste or odor as depletion indicators. However, metering is seldom practical outside testing laboratories. Integral or optional by-pass valves provide a means of obtaining unfiltered water for nondrinking and noncooking uses. Allowing water to run through the filter for at least 30 seconds before filling a container helps to remove bacteria that may have accumulated within the filter. Some filters may contain silver.
Manufacturers claim that silver discourages the growth of bacteria within the filter.
The Environmental Protection Agency, however, has concluded that silver compounds in water filters have little bacteriostatic effect. Fees for a licensed plumber increases the initial cost of some models. Installation cost may be included in the purchase price of reverse osmosis units. Copyright 1999 University of Missouri. Published by University Extension , University of Missouri-Columbia.