Don Walters
: We live in a split level house with a crawl space. : When doing the laundry, we get septic tank odor in the : crawl space and in the laundry room. The washer drains : into a 2? pipe which connects with the 4 sewer pipe : which travels approx. 25 to the crawl space. There it : turns 90 degrees and exits through the outer foundation : and into the septic tank. We can control the odor in : crawl space by venting it with a small fan but the odor : in the laundry room is overpowering at times.Don,Whenever you flush the toilet, do the laundy, or anything else that causes water to fill into your septic tank, the incoming water displaces the air in the headspace of the septic tank. The displaced air exits the tank through the leach field, or dry well, or escapes through a vent(s) installed in the plumbing system.In your situation, the displaced air is venting up through the 2 washing machine drain pipe. This is what is causingthe odor problem in your laundry room. There must be anadditional discharge point in your crawl space.The fix the problem you need to do two things:1) Confirm that there is a 4 vent pipe on your system This pipe normally exits your house through the roof. Its a good idea to check this pipe to obrtructions like bees and birds nests. If there is no vent, or the vent is smaller than 4, you will need to have your system upgraded2) A vented trap is necessary at the point where your 2 washing machine drain enters the 4 sewer pipe. Keep in mind that this trap will only work if there is a proper vent as described above.Good Luck!Roger H. Saugerites, NY2
