Replace Whole-House Water Filter Cartridge

Shut off the main water supply. Open a downstream faucet to release pressure. Use the filter wrench that came with the housing to unscrew the sump (big blue or clear bowl). Remove the old cartridge and dispose of it. Rinse the sump with clean water and wipe it dry — look for cracks or sediment buildup. Lubricate the O-ring with food-grade silicone grease and seat it in the groove. Insert the new cartridge (match the micron rating and type: sediment, carbon, or multi-stage). Hand-tighten the sump plus a quarter turn with the wrench — do not overtighten. Slowly turn the water back on while checking for leaks. Change more frequently if your water supply is heavy in sediment or the pressure drops noticeably. A clogged cartridge strains your pressure and can crack the housing, flooding the area.