Hi everyone, I have a drain obstruction which is causing a back-up into both my downstairs shower and toilet. I had a plumber out after snaking the line myself did not solve the problem. He informed me that the pipe has broken, or been crushed. After he left I noticed a clean out in my closet connected to the drain line from the clothes washer. I ran the washer to make sure it would still back up. To my surprise the water drained properly with no ill effects in the house. I went outside and looked in the drain access coming up out of the lawn, and could see water flowing rapidly to the septic tank. I am wondering, does this indicate that I have a two drain lines? One for the washer, and another for my sinks/tubs/toilets? Also: I went up to the roof and found two vents, would this also indicate two drains?