Drain smell due to back draft......?

Dinarius

My kitchen is smelling a bit and I think it's due to a backdraft from the outflow pipe.

I have no doubt that the cowboys who built this place didn't do what they should have done, so, what can I do to stop this?

I have tried using overnight drain unblocking liquid, just in case it was caused by a build-up in gunk in the U-bend of the outflow pipe under the sink. But, this hasn't solved the problem.

Should there be some kind of 'trapdoor' that stops gases from backdrafting?

Thanks.

D.

maninaskirt

I had this problem in my utility room, it turned out that I never had a " TRAP " fitted to the waste pipe of the washing machine causing the sewage smell to come back up the pipe, anygood hardware shop will sell you a " trap " for this purpose, it cost me €14 for the whole kit and cured it overnight, same applies for dishwasher, etc. hope this helps you.

Alun

In our case this was mainly due to the pipe leading to the outside from the washing machine not sloping downwards towards the outside. In fact it had sagged a little and there was water accumulating in it. Solved by just wedging some small blocks of wood under it to get the proper gradient. It should also have had a trap built in, but it was almost impossible to fit one after the fact because it was behind some fitted kitchen units, but any remaining slight smells were banished by the simple application of some duct tape around where the washing machine hose entered the top of the pipe.

tk123

Hey this is happening in my office except there's water coming back up the drain into the sink and stinking the place out! We are in East Point and the port tunnel works are right beside us. From what you guys are saying - is this just down to bad plumbing!? The sewarge smell makes me feel sick/gives me a pain in my stomach..

rooferPete

Hi,

It's unusual for water to back up a waste pipe with a trap under the sink, the purpose of the trap is to form a water seal to stop the smells coming back into the room.

You may have a general drainage problem, because a waste pipe blocking is not unusual but a pipe backing up is often caused by the waste pipe running into a soil stack that is not clearing fast enough or it may need an anti syphon valve fitted.

Wobs

Hi,

I had the same problem a short while after moving into my place. The problem was that the drains outside were full of rubble from when the place was being built. The combination of rubble and kitchen waste (food particles, oil etc.) blocked up the drains. Cleared out the rubble and problem was solved.

Before anyone says it I know not to pour oil and grease down the drain, it was just the small amounts from washing dishes that built up over time.

tapest

Hi

You mention "U bend", which I assume means a trap. As RooferPete says water in trap will stop smells. Are you sure the smell is not coming in from the outside....ie sewage smell. Check the obvious cause...Is there a 4" vent pipe and is it high enough . I've seen some lovely "closed systems".
t

magpie

Have the same problem in my place, smell emanating from dishwasher and washing machine. Fixed the washing machine by taping up around the pipe with gaffer tape, will attempt the same thing on dishwasher later.

I had an architect around (we're building an extension) and he said that the drainage outside was very 'high', the pipes only seem to run about 3 inches under the level of the pavement outside. I presume lack of gravity draining off the pipes is contributing to the smell.

rooferPete

Hi Magpie,

Main sewer pipes don't need a big fall, in fact you could put them on the surface so long as they fall away to the main drain.

tapest could spot on, check the soil stack actually vents three feet above the highest window (old rule might be changed).

I have come across exactly as tapest described because so many new soil pipes are boxed inside and vent at tile vents in the roof.

There may be a lack of communication between plumber and roofer because I have had to remove caps off the soil vents and connect them to the tile vents.

The same thing can cause the soil pipes to back up or syphon off the sinks and showers.