We’ve lived in our new house for one month. There is a pungent broccoli and dirty sock odor coming from one of the three bathrooms. Prior to moving in, the plumber dug up the slab to add a shower and moved the drain for the tub. This is a one-story and all drains in the bath are going to the same roof vent. To eliminate the odor, the plumber dug up the new shower drain and added a “P” trap. The plumber ran cold water down the drain to keep the “P” trap moist. The next day, the septic tank was inspected, pumped and cleaned. There is no blockage from any of the drains and the drain field is not a problem. The smell went away for a couple of days. Then after I washed two loads of laundry, the smell was back. We have not used the shower due to the odor. The odor is not continuous and only smells after I use the washing machine. Can anyone help me with this problem?

"To eliminate the odor, the plumber dug up the new shower drain and added a “P” trap."
Are you saying the shower was installed without a "P" trap letting sewer gas escape into your home? Unbelievable! Or did he double trap the shower? Illegal! How many more fixtures aren't in your home aren't trapped?

"The odor is not continuous and only smells after I use the washing machine. Can anyone help me with this problem?"

You have a partial blockage downstream from the shower. Let me explain what's happening. The washer pump discharges with great force. This discharge races down the sewer and bangs into a partial clog and bounces back sending a bubble of sewer gas back up the line. The gas escaping from the shower trap is what you smell. After bouncing back the water drains past the clog. To fix this problem the drain line downstream from the shower must be snaked and cleared. Good luck, Tom

It could also be a situation of the washing machine discharge branch being positioned in a way that causes it to suck the water out of the trap in the shower which then allows open passage for sewer gas. I see that this dialogue was posted many months ago, just thought I would throw in my two cents for anyone with a similar problem.

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Originally Posted by stacytodd

It could also be a situation of the washing machine discharge branch being positioned in a way that causes it to suck the water out of the trap in the shower which then allows open passage for sewer gas. I see that this dialogue was posted many months ago, just thought I would throw in my two cents for anyone with a similar problem.

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The only way this could happen is if the washer trap and standpipe were unvented. And that's not very likely. Regards, Tom

Considering the previous post concerning the untrapped,(or double-trapped) shower drain, perhaps the washing machine discharge riser/branch IS unvented, I see many add-ons where this happens although that is a particular clarification I should have mentioned. Thanks. I know who to ask when I'm stymied :)

Considering the previous post concerning the untrapped,(or double-trapped) shower drain, perhaps the washing machine discharge riser/branch IS unvented, I see many add-ons where this happens although that is a particular clarification I should have mentioned. Thanks. I know who to ask when I'm stymied