we have a downstairs laundry room. The drain for the washing machine has become clogged. The upstairs kitchen sink seems to drain down to the same pipe as our washer. We have a septic tank. The washer pushes water out at a great rate of speed which is when the water backs up through the drain pipe. Do you recommend using Drano from the upstairs sink or thru the washer drain pipe, or both?? I have a feeling that the upstairs sink has a clog down at the basement level and the washing machine outflow hits up against it and flows back thru the drain pipe. Any suggestions??