Same model as our Flagstaff 831FKBSS
It's located in a compartment in the bathroom on the same side your city water connection is located. Bottom of a linen closet, you'll need a screwdriver to loosen to screws on the side with only one hinge. The filter is in that compartment with your water pump and your winterization inlet into the pump. Be sure to place a towel in that compartment before you remove the filter canister. Dump water right into sink or toilet. Wash out canister and replace filter. Be sure the gasket on the canister is in place before you reinstall and do not over tighten the canister. Oh make sure water is off before you start any of this. Good luck
