How Often Should Water Filters Be Replaced—and What Does Maintenance Cost?

Filter replacement is not governed by one universal calendar. The appropriate interval depends on the product, its rated capacity, feed-water quality, household use, and the manufacturer’s directions. EPA advises owners to follow the filter’s instructions carefully. EPA filter maintenance guide (opens in a new tab)

Some cartridges have a time-based replacement interval; others also specify a gallon capacity or include an indicator. A filter exposed to unusually high sediment or heavy use may need attention sooner. A noticeable pressure drop or change in water quality can be a reason to inspect the system, but neither symptom alone identifies the failed component. A system can also continue to flow while its rated treatment capacity has been exceeded.

Maintenance cost should include more than the cartridge price. Consider how many stages need replacement, whether parts are proprietary, whether labor is needed, how often a service visit is recommended, and whether the system needs sanitizing or a performance check. For softeners, salt and occasional cleaning or service may be relevant; UV units and RO systems have their own model-specific service requirements.

Keep a simple record: system model, installation date, filter changes, service, water test results, and any alarms or changes in flow. That record helps the homeowner follow the manual and makes warranty questions easier to resolve.