Hello all! I have an older fifth wheel (2004) with a crack in the black tank, we took off the metal sheeting and we can see it, maybe 5"-6" long or so, and the water is coming through it pretty strong. It's in the side of the tank. The only dealership we can get to doesn't handle hazmat and won't replace it for us. At the moment we've exhausted every avenue and our only option is to try to patch it ourselves. When we asked about what we should use to patch it, the dealer said the tank is made of "some kind of molded plastic." That was all the advice they would give. The best we can think of is Flexseal tape. Does anyone know in more detail what the tank is made of, and what would work best to patch it?