All ActivityMost RecentMost LikesSolutionsRe: Very cold weather, toilet overflow, sink tooI just want to thank everyone for your help. Yes, my bathroom sink empties into my black water tank, and that was the problem. I made the assumption that grey goes to grey, black to black. Same reason I have a problem playing Wheel of Fortune. Thanks again.Re: Very cold weather, toilet overflow, sink tooIssue resolved. Thanks again for all the help. And thanks too for not letting me have it for not even saying what model I have--though the problem, and the suggested reasons and fixes, were spot on. I have a class C Minnie Winnie. So, I bought a new toilet for nothing. My problem was the same one that causes me to lose when watching "Wheel of Fortune", assumptions about where things are coming from--or going. I assumed that grey water went to the grey tank, and black to black. A quick look told me that several of you were right, my bathroom sink drains straight into the black tank. Once I understood that, everything made sense. Also, the idea of keeping a better eye on the levels is, unfortunately, good advice for a RE active RVer like myself. I need to check my sensors and make sure they are working correctly, maybe put on new ones. Has anyone ever used the "sensor" cleaner they sell in the RV stores? I would rather try that than crawling around, but don't know if they will "clean" an encrusted sensor. I know they wont fix a bad one. I'll use the FAQ and forum history from now on before I post. I did a search, but most overflows are valve failures--my original jump-the-gun response. thanks, HalRe: Very cold weather, toilet overflow, sink tooThanks for all the replies, they are all helpful and give me some ways to go. I will definitely see where the bathroom sink is plumbed to. Oh, ha, I was just kidding about the monthly shower. You all have been very helpful and I appreciate it. HalVery cold weather, toilet overflow, sink tooHi, I'm about two years a full timer, and I'm stumped, which is something you can't be if you are on the road. I'm at the border/panhandle of Florida/Alabama. The weather has been in record lows, freezing or below. Two weeks ago my toilet over flowed, what a mess. One time, no apparent reason (release valve no hanging on Aqua Magic IV); o.k. a fluke--flukes being scary as hell while RVing. Then again, another cold snap. I had: water dripping to keep the water hose from freezing shut--but the water tanks wer--I think, yikes--pretty empty; exterior shut off on black water shut; exterior shut off on grey water open and hose exiting at a good angle. I said a bad word, compared replacing the ball--toilet seal--valve, and the water release valve to a new toilet, and got a new Aqua Magic V. (Off the subject, but much more flimsy that the IV, but I like the univalve action on the hand model.) Last night, below freezing. Water in a pencil-lead stream in bathroom sink and kitchen. And, the water overflowed in the bathroom sink, AND was ready to overflow in the toilet--caught that one. On "flushing" the toilet it looks like a cherry bomb had gone off in the tank, the water boiling up I pulled the flush arm. So, I don't pay good attention then. I ran outside and opened the black water exit valve. All water disappeared--except what was on my carpet, again. I just don't get it. My water exits are simple, one big one from the black tank, and a smaller one from the grey that joins the larger black exit pipe near the drain hookup. Nothing tricky. Soon as I opened the big valve on the black water, everything drained, like swoosh. I think I threw away a good toilet, and bought one I didn't need. It's hard to think when the toilet is overflowing. I don't get what's happening. I am certain it has to do with water freezing somewhere. The big puzzle is why an over flow in one tank (sink) could relate to an overflow in the other. There could have been a coincidence. That is, I simply wasn't watching the condition in the grey tank--I took my monthly shower yesterday. Because I can't pin it down it keeps me at a low level of being freaked out. The cure for the symptom is, for very cold weather, turn off the hose, turn on the on-demand water pump connected to the onboard water supply. Then turn it off at the wall switch, then on when I want to use the water to wash or flush. But, I'd like to solve my problem. Long post, thanks for reading and any suggestions Hal P.S. Put a good hair dryer on your list of RV essentials. It's unfrozen stuck valves after freezes, dried carpet, and lots of other stuff. Andy I guess it would dry my hair though I've never used it for that.