One simple way to decide if it is time to use a replacement water filter is if the sink begins to loose water pressure; the sink will loose water pressure because the filter is clogged with dirt or other sediments. Depending on the microns the filter is able to keep out of the water some units may be washed out and reused for a time; usually if a filter stops less than 5 microns from escaping the filter, rinsing out the filter is useless.

A good rule of thumb is that an average household will use about 600 gallons of water per month from their kitchen sink for drinking, cooking, and cleaning; using the replacement water filter before the water actually starts to taste or smell bad is a good idea, however waiting until there are signs that the filter is loosing effectiveness is a good idea to prevent waste.

Whole House Units

Whole house water purification systems are the most practical for homes with hard water or contaminates which irritate the skin because impurities such as lead take a time to dispel with most whole house units and are treated more effectively using point of use or under the sink units.

Using replacement filters for whole house units is very similar to using replacement water filters for countertop/ under the sink units; the difference will usually lie in the amount of microns it filters. Whole house units in general allow more contaminates to pass to provide adequate water pressure for the entire home; as a result many of these replacement water filters can be rinsed out to prolong their usefulness.

Lessening water pressure is a good sign that the whole house water filer cartridge needs to be replaced; though these types can be rinsed out, it is a good idea to only rinse them one time before using a replacement water filter cartridge.

Also if a peculiar smell or taste returns to the water a replacement water filter cartridge is also necessary; most water filter cartridges will last for three or four months in whole house water filtration units.