Peter H wrote:
Hi hope that someone from this excellent group can help with this one.
It's sure got me scratching my head.

We have a main-floor laundry room with a sink in our two story home.
The washer drains into a pipe that joins the sink drain prior to the p-
trap. Every week or so we've noticed an awful smell in the laudry
room, which I suspect is a sewage odour, as if the p-trap has lost
it's prime. If I run water down the drain the smell eventually goes
away.

I've checked under the p-trap but can't find any water there and don't
think the joint is leaking. It's as if something is sucking the water
out of the trap, but have never heard of this before.

The house is located in the greater Toronto area in Canada. The street
has a gentle slope to the south. We have an apartment in the basement
of the house, with a full kitchen and bathroom. The second floor has 2
bathrooms, but nothing directly over the laundry room.

We've taken to just leaving the stopper in the sink as a temporary
measure, but obviously would like to resolve this problem.

Thanks for all replies.

Peter H

A common question on plumbing license tests.
http://www.managemylife.com/mmh/ques...raps-lose-seal