Assuming you are referring to the Aquasure RO filter, below are instructions on how to change it:
1. Locate your filtration system and identify the filter housing. Depending on your model, it may be located under your sink or in your basement near your water heater.
2. Unscrew the housing cap counterclockwise and remove it. Some models have a release button that must be depressed before unscrewing the cap.
3. Remove the used filter cartridge from the housing and discard it properly. Inspect the O-ring seal at the base of the cartridge and replace if necessary.
4. Insert the new filter cartridge into the housing, being careful not to touch the filtering material with your hands or allow any dirt or debris to come into contact with it. Screw on the housing cap clockwise until snug. Be sure not to overtighten as this could damage the O-ring seal.