We've had a washing machine in the basement for more than a decade (we use it for oversize stuff, horse blankets). Suddenly, upon replacing our old failing machine with a newer one, I'm smelling a whiff of sewer gas in the mudroom where there is a sink that appears to be draining into a Y with the washer drain pipe. Why now, suddenly? I'm looking at the washing machine manual, and it says not to install the drain hose deeper than 8" into the drain pipe, but I don't think the installer did that, I was there and there was just enough hose to make it without an extension. I can cut the zip tie and look, of course... But what else could explain this, given I have a notoriously good sense of smell and this has never ever happened before? Thanks for any ideas.

1 Answer 1


The new washing machine is more powerful than the old one and is probably sucking the water out of the trap on the 1st floor. You either have a partially? blocked vent stack or the washing machine waste pipe was always under-vented and your new washing machine is making it apparent.

  • Thank you. I'm sure it's more powerful. How do I determine whether it's a blocked vent stack (and clear the block), if (hopefully), that's it? Shame on my plumber for under-venting, if it's a more complex fix... Happy New Year!
    – Melissa
    Commented Jan 4, 2022 at 23:15
  • @Melissa a plumber with a bore scope will be able to look up the pipe from below as well as down from the vent that’s on the roof. It could be blocked from a bird’s nest or an animal dropping nuts down the vent or debris from nearby trees… Commented Jan 5, 2022 at 1:52
  • Thank you both, and Happy New Year!
    – Melissa
    Commented Jan 5, 2022 at 23:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.