Why does my upstairs sink and wahser machine flood the floor drain in the basement? Every time I use the washer machine or wash the dishes in the upstairs sink it flood the floor drain in the basement, and if I am washing clothes I have to stop the water from draining into the washer sink in the basement by openeing the washe door and letting the water run out so the water doesn't flood, it is ridicoulous and takes for ever to wash my clothes, and now it has got so bad that I am washing dishes in the tub because the bathroom tub and toilet and sinks doesn't flood the basement at all, what do you think the problem is?