If you have a cartridge-based water purification system, it is inevitable that you will have to change the filter. Ordinarily, this is a relatively simple task, but if the filter cartridge is stuck, it can take multiple attempts before you can successfully remove it. If you are having trouble removing it by hand, there are a few other methods you can employ to dislodge the stuck cartridge.
Try to dislodge the stuck filter cartridge with your hand. Hold the base of the unit and apply pressure while turning the cartridge counterclockwise. If the base is at the top, turn the cartridge clockwise.
Use a hard plastic wrench, if one came with the unit. Put the wrench on the cartridge and turn in the same directions noted in Step 1.
Use a pair of needle-nose pliers to dislodge the cartridge. If the cartridge is unscrewed but not separating from the base, wedge a pair of pliers between the base and the cartridge. Lightly apply pressure against the cartridge until it separates from the base.
Apply a small amount of heat to the outside of the base enclosure with a hair dryer. Start by applying heat for 30 seconds. Too much heat can warp the enclosure. After applying the heat, try again to dislodge the cartridge using the methods listed in Steps 1 to 3.