Aquasana Replacement 20-Inch, Sediment Pre-filters for Whole House Water Filter Systems, 4-pack Replacement 20-inch, sediment pre-filter for Aquasana Whole House Systems (4-pack) Use genuine Aquasana replacements only - untested replacements are not certified for performance capacity or contaminant removal Designed to prevent dirt and sediment particles from entering and clogging the main filter unit Replace filters every 1-3 months depending on water quality and sediment levels - when color darkens or water flow slows Replacements made easy - no plumber required