Recently had a flood due to sanitary sewer backup. The county came out and cammed my sewer and he told me I have 5” clay. To my knowledge a 5” backwater valve does not exist. Would it be recommended for me to adapt up to a 6” valve then back to 5”. Or could I get away with a 4” backwater valve? If I can get away with 4” that would be awesome. Parts are way cheaper and more plentiful. Thanks in advance.