We were spending the winter several years ago in a southern state park with full hookups. After about a week I noticed my sewer hose was out of the hole. I put it back, but within a few days noticed it was back out. I was telling one of the park rangers about it and he said it happens once in awhile. For some reason there was a pressure at times that would pop a hose out. My curer to that was place a cloth bag with about 10 pounds of sand in it over the hose. No more problem. I carry the sand bag with me now in the water bay, if dumping and I don't have any other way to weight the sewer hose I get the bag out.