To expand on my question of leaving the popup popped in and unheated 32x48 pole barn w/o insulation; I'm winterizing it now and considering not putting antifreeze in the lines (at least yet maybe later in the winter) in the tank and water lines. I've blown out the water lines, hot water tank, low points, external shower, etc. We might be going to the property a few times before the snow gets crazy, and I'd like to use the tank / water / toilet while there. You think I could fill the tank while I'm there and be safe with re-blowing out if I were to take the air compressor and blowout after each use? I thought I remember someone saying they only ever blew out lines, but they may have lived in a more mild climate than northern Michigan! EDIT: I thought better safe than sorry, and added antifreeze. I'm not sure when I will be closing on the property and didn't want to risk it!