Someone mentioned it's a good idea to install a backflow preventer on the house sewage line.
I searched google for such product and found a few different ones of different shapes and prices, some are called backwater preventer, some called flood guard. I still have no idea which is the correct type.
Could someone point me to the correct type to use for a family house? I have access to the sewage drain pipe (4-inch black plastic pipe) in the crawlspace and would like to install myself if it's just a matter of cutting the pipe and inserting the device.