Quote:
Originally Posted by rrohrer
For several yrs now with my older camper I have always left about a gallon of water in the black tank. dumped in after disconnecting along with rv treatment to keep tank clean. I never emptied at end of season with thought- told to me by another camper that this is not enough to cause issue. I looked at my camper and saw some insulation protruding around the sewer outlet pipe and the cover around this area seemed swelled. I got paranoid that tank burst. I'm not sure that's the case and plan to go back with tools remove cover and look. Question- is this unsafe practice. how easy can tank crack? and how could I fix if it is cracked??
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The concern is that the first gallon or two of liquid in a black or gray holding tank occupies the lowest part of the tank which includes the drain fitting and the dump valve and maybe a couple of inches of pipe between the valve itself and the tank. Remember that freezing water breaks things as it expands in an enclosed area, so it is possible that there could be some freeze damage in that area because part of it is enclosed. If there were no drain, a gallon or two of water simply laying on the bottom of a tank would not be able to cause expansion damage because there is no enclosed space.
My personal opinion is that both tanks should be drained as dry as possible of water before winterizing. When I winterize, I blow out the water lines with the dump valves still open. After letting them drip for a few minutes, I close them up and pump the pink stuff into the system. Typically a few cups of pink RV antifreeze ends up in each holding tank and a bit in the toilet. It should help keep the seals from drying out. And if there is any residual water on the floor of the tank that didn't drain out, the antifreeze lowers freeze point enough that it can not cause a problem.
If one lives in an area where it's possible to camp year 'round, but there still might be freezes, I'd advocate draining the holding tanks as dry as possible after blowing out the water lines and draining the HW tank. If things are clean enough, I'd even think about leaving the valves to make sure no water accumulates up against the valve or in the drain pipe.
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