I use a 10year old RoUltratec 100gpd system with an add on DI unit for one and a 5 year old ebay 100gpd Water General with a DI add on. Both have been fitted with Spectrapure's silica busting membranes so they've been reduced to 75gpd. My Roultratec also supplies my refridgerator's water/ice upstairs before the DI.