We bought a house 10 years ago with the clothes washer in the basement. The drain line ran to a (dedicated) trap just before entering the main septic line where it exits the foundation to the tank. We recently moved the washer to the first floor and I ran the drain approx 45 feet to connect with the existing drain line. I also installed a trap at the washer at floor level.

I haven't had any drainage problems, but am wondering if this is a potential problem. The drain is dedicated to the washer only and there is no vent. We were getting sewer gas before I installed the trap at the washer. Now there doesn't seem to be any smell.

Does the second trap (the original one) need to be removed (a stinky job)? Or do I need to vent the pipe?

Any info would be appreciated. Thanks,

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Does the second trap (the original one) need to be removed (a stinky job)? Or do I need to vent the pipe?

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It's a code violation to double trap any fixture. Remove the trap next to the main. The original set up had the washer discharging into the sewer without a vent. If you wish to remain in code and the drain line is 2" you must install a vent not over 8 feet downstream from the trap. if code allows this vent can be a AAV,(air admittance vent) or if a AAV"S not permitted you can run a vent out the roof or revent back into a dry vent. But the vent MUST be a dry one. Good luck, Tom

Thanks Tom for the quick reply. Not a job I'm looking forward to. What makes the double trap a code violation? Is it a danger due to gasses potentially getting into the house? Just curious. Got to go get some PVC...

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Originally Posted by Floyd11

Thanks Tom for the quick reply. Not a job I'm looking forward to. What makes the double trap a code violation? Is it a danger due to gasses potentially getting into the house? Just curious. Gotta go get some PVC...

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The reason is that the trap next to the main could suction water from the second trap lowering the trap seal allowing sewer gas to enter your home.
This is addressed in Chapter 7, section 703.5, (Double Trapping) of The Standard Plumbing Code. Regards, Tom