Why does my drain smell like sewage even when clean?
Sewage odors vent directly into the room when water inside the P-trap dries out or drains away, breaking the liquid seal that blocks sewer gas. Standard cleaning and replacing pipe hardware won't fix the smell if the trap simply lacks water to maintain that barrier.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Put some mineral oil in the trapDid this help you?
- 2Install a trap seal primer to continuously add waterDid this help you?
- 3Manually add water when the trap is dryDid this help you?
- 4Checking for a clogged roof vent stackDid this help you?
- 5Checking if P-traps are being siphoned dryDid this help you?
- 6Blocking the path below the trap and filling the sink with a bleach solution to soak the overflowDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Laundry is on the second floor and there's sewege smell every once in a while. I'm trying to figure out if it's a dry p-trap or something else.”source ↗
“One bathroom in our house has a smell coming from both the sink and the shower.”source ↗
“The p-trap is not clogged and it still smells even after it’s been cleaned out.”source ↗
“I hired a plumber and he replaced pretty new plumbing under the sink and that didn’t help at all.”source ↗