When to Replace a Whole-House Water Filter, and What Sets Its Lifespan

A whole-house filter has no single lifespan: its cartridge or media lasts for the capacity its maker rates, counted in days or gallons, and the EPA’s maintenance guidance for filters certified to reduce lead says to follow the manufacturer’s instructions exactly and to change the cartridge on time.

What decides how long a filter lasts?

The EPA says filters have cartridges that wear out and become less effective with use, and that each filter type, brand and model can be a little different. The same sheet notes that running large amounts of water through a filter wears it out faster. A whole-house filter treats every gallon the household uses, so a busy household reaches the maker’s rated capacity sooner than a quiet one. Its fact sheet is written for filters certified to reduce lead in drinking water, so treat it as the principle and your maker’s manual as the answer for a whole-house system. For that reason the maker’s rated capacity for your exact model is the number to use, not a general estimate from a website.

How will I know it is time to replace it?

Some filters have indicator lights that alert you, according to the EPA. When there is no light, the agency says to track the days or gallons used after installing a new cartridge and to set your own reminder to change it. Write the date and the maker’s change interval on the housing or in your phone the day you install a cartridge.

A drop in water pressure at the fixtures, or a return of tastes and odors the filter used to remove, can be a prompt to check the schedule early. They are signs to look into, not proof that the cartridge is spent.

Does it matter which cartridge I buy?

Yes, because the EPA advises using a cartridge that is compatible with your filter and following the manufacturer’s instructions to change it. A cartridge that fits the housing but is not made for it may not do the job the housing was installed for.

When should I stop and call someone?

• Contact the manufacturer if you have questions or problems with the filter, as the EPA advises.
• Call a plumber if water pressure falls across the whole house after a change, or if the housing leaks.
• Ask the installer for the maker’s change schedule in writing if you did not receive one when the system went in.

A Filter Lasts as Long as Its Rated Capacity Allows

Look up the rating for your model, mark the install date, and treat the first sign of a pressure drop as a reason to check the schedule rather than a reason to guess. A filter that is changed on time does the job it was installed to do, and one that is left too long may not.