Answer: -We have this same problem. I have moderate luck using heavy doses of "Clog Gone" peroxide-based drain cleaner, but I still have to snake the line out every two or three years. I go in through the cleanout in the floor drain. You can lessen the problem somewhat by installing a backflow valve in the floor drain. This is a sort of ping-pong ball and a metal collar that screws into threads in the floor drain (under the perforated cover). But if you do this eventually you will have trouble with water backing up in the laundry standpipe. -One of mine basement pipes clogged solid last week. Even the "professional" drain cleaners didn't work and, unfortunately, there was no available cleanout. However, there was a rubber collar I used to connect the kitchen PVC to the cast iron drain pipe. I removed it and there was just enough of a gap to slip a hand snake in there. That didn't work either, but a power snake on my electric drill did the trick.