Mike, My guess is that at a minimum you should replace: Filters Membranes Membrane tube seals/O rings HP pump oil Probably HP hoses...if they do not leak when you start it up, they probably will within a few months because of dry-rot. Pat, I did not buy the pleated/washable filters at Home Depot. I bought 6 each (5 micron and 20 micron) in Darwin at a large hardware store. I think you will have difficulty finding 25 micron, except in The EU. The 20 micron is a little tighter, but the Dessalator feed pump on the 160 liter has no problems with it. Bill BeBe 387