smell from sewer...

4odh4n

we are having intermittent problems with a smell in an upstairs en-suite that I cannot figure out. The smell is very sewer-esque and has to be somehow venting back into the room anytime the water trap seal is broken by flushing the toilet or running a tap etc.

All smell traps are present on the toilet, shower and sink etc and there are no problems with smell in the main bathroom upstairs or toilet downstairs.

The en suite is between two bedrooms so there is about a 4m run under the floor to the outside, then down the wall and into a manhole. Downstairs toilet is directly below the en-suite with same 4m run to outside and into the same manhole (does not link up with en-suite pipe before manhole), there is never a smell in this toilet.

Originally the pipe from the en suite just turned down the wall with no vent stack. So last year i put a stack onto the pipe and ran it up to roof level, to match the stack on the main bathroom to see if it would help, the main bathroom discharges to a second manhole before running into the same manhole as these two toilets, then to the sewer. I think the vent helped a bit, but sometimes a smell still appears when the toilet is flushed or a tap is ran. Is it a case that the gas is getting held in the 4m of pipe under the floor, as opposed to if the toilet was on an outside wall and there would be no length of pipe?, I had hoped venting the pipe would have prevented this happening.

My other notion is that the pipe under the floor has maybe moved and has lost some/all fall so is not emptying completely, but would this be enough to cause a smell in a bathroom that is used every day?

Think my next move is going to be to lift the toilet to make sure the pipe has a fall, but would welcome any other suggestions that might help me figure this out!!?!..

Kimbot

I had this happen in an En-suite of a house we rented years ago. We went out and opened up the manholes to find a blockage caused by someone throwing Baby Wipes down the loo and they all just ended up clogging up the pipes. I would suggest going looking for a block like this as ours wasnt obvious.

foxy farmer

Wind speed and direction gives me trouble from time to time. If I'm in the main bathroom on a wild day with wind from south east south or southwest i can hear the water in the bath trap gurgling and after a while the water will be sloshed out of the trap and the sewer smell will become apparent.
I heard that flushing large wads of toilet paper can pull the seal by creating a vacuum as it runs full bore down the stack.

antoinolachtnai

Are you sure the seal where the toilet goes into the 4" sewer has not perished?

the_pen_turner

is there a vent on the stack