The resevoir serves more of a purpose as a pressure tank so that if you're pouring drinking water you're not doing it at the rate of 100gpd. I think paint dries faster, lol. That isn't the unit that I have. Mine is from FilterDirect and I'm very happy with it. I don't know anything about the one you're looking at though. You may try to do a search here for that seller name and see if you come up with any info good/bad. I don't have a resevoir on mine and never felt like I needed one. I just turn it on and go back to it in a couple of hours.