HOW TO CHANGE A GXWH20S FILTER
You need to cut water supply to filter, you may want to put a bucket or something to catch water under it, then, press the button on filter to release pressure in filter. If you have a wrench for it, the wrench should slide up from bottom and engage ribs on side of filter. Turn counter clockwise to remove, sometimes you can do this by hand. You can also use a strap wrech, just don't break canister. You also want to try not to strain your pipes if they are not supported. Any way, you may have to figure a way to grip canister to twist off. You do not want to overtighten for this reason. After you change your element, make sure the o-ring in the lip inside of canister is in place. Twist back on, clockwise. Turn your water on and check for leaks.