I'd start by cleaning out all drains thoroughly (snake them if necessary).

Then address humidity issues. The poop smell might be mustiness caused by damp air around older items that you have stored in the basement. We had this issue with a storage closet in our house. It had a couple boxes of old papers and clothes from my husband's childhood home and then high humidity in the house released all those smells which are, um, "earthy."

We cleaned out that closet and got rid of anything that smelled very bad, sealed the rest in plastic containers instead of cardboard, and then dehumidified the closet (ran a dehumidifier for a day and then installed charcoal moisture absorbers that are replaced periodically to capture additional moisture).

Poop smell gone.

We have a kitchenette in our row house basement that we almost never use. Whenever I smell that smell down there, I run the water in the sink for a few minutes. It always gets better, so I assume that’s the issue. Do you have a rarely used drain down there!

If you have a floor drain, pour some bleach in.

How long does it take a p-trap to dry out? The sink, shower, and toilet all get used at least once a day…

Anonymous wrote:It's probably a floor drain where the trap has dried out and sewer gas is leaking in. If you fill the trap with mineral oil it won't evaporate.

This 👆🏻 It could also be from a pipe but both are easy fixes.

https://www.benjaminfranklinplumbing.com/expert-tips/drains/are-stinky-sewer-smells-wafting-out-of-your-drai/#:~:text=Fill%20the%20Trap,as%20running%20a%20little%20water.

Anonymous wrote:It could also be something dead in the walls.

+1 dead mouse

Or busted or leaking sewage pipe. The big pipe

It could also be something dead in the walls.

Do you have a bathroom down there? If the ejector has water in it this can happen.

I’m in a rowhouse, not DC and experiencing a similar problem. I have called plumbers out numerous times and I’m determined to fix the issue once and for all now. So far I’ve been doing process of elimination. First it was making sure there was water in all the p traps in basement. A couple of weeks ago I got the grease trap removed. Next the plumbers are coming back out to do another smoke test. Fingers cross they find the issue once and for all.

Is this new issue or old issue?
Call a plumbing company.

1st thing is to run some water in every drain you can find.

It's probably a floor drain where the trap has dried out and sewer gas is leaking in. If you fill the trap with mineral oil it won't evaporate.

Live in a dc row house. On and off my basement will smell like sewage. No clear issues with backups or anything. Could it be my neighbor? How do I figure out where it’s coming from and what to do about it? Do I just call a plumber and tell him that issue? Help!