I live in a trailer, so my sewer line is above ground, with the clean-out plug between 12" & 18" above ground. During the cold winter in arkansas the toilet paper tends not to flow. Each trailer , there are 12 in line with my trailer being #10. We all tie into the same drain line. When the line get clogs at trailer 11 and/or 12 the back-up from trailers 1 thru 10 tends to fill my bath tub & over flows my toilet. My question is.. Is there some sort of check valve or a flapper system i can install that will prevent the this from happening and still operate properly when the main line is flowing/draining correctly? Thanks to all who respond with any advise.