@grey @IsraelDelendaEst @wizardmanperson @bronze Which filters are needing replaced? My idea for my sanity and wallet is to first run an inline pre-filter I change annually. Something like pic rel which claims 12 months or 5k gallons. That would function similarly to the first filter in a 3-stage RO, I reckon. Maybe use one of those for the final stage of yours has a post filter as well. I can't speak for the brand of course, but you might be able to find a substitute tank and filter on ebay of all places.