I have a basement with a 1973-74 mobile home with septic field. Basement drain backs up when washer is used. Sandy area, no drain plans to see if basement drain goes into septic or not. Anyway I can tell if maybe a pipe is plugged or cracked without tearing out the floor?
Thanks. Borage

Run the washer until the floor drain backs up, then flush a toilet and let me know if it backs up even more. If flushing the toilet makes no difference, you should be able to snake from the washer drain, or the floor drain to clear the partial blockage in that pipe. If your floor drain has a side clenaout plug, I would suggest getting it out and snaking from there. Please let me know how things work out. Should be no need to break up any concrete at this point.

Now, if when the floor drain is backed up from the washer running,and you flush a toilet and it backs up even more, I would suggest checking the septic tank to see if it "full" when the drain is backed up.