Smelly bathroom

Hello everyone

We have a bathroom on the top floor of our house (4th, inc basement), and more often than not there is a lingering smell, often quite sulphury, that seems to eminate from the room in general, rather than anywhere in particular, and there are no obvious leaks or blockages.

We only use this bathroom to bathe our daughter in the evening, and to occassionaly go to the loo.

When we flush the loo, it helps get rid of the smell, but it soon enough comes back.

We have another bathroom downstairs which we use on a more regular basis, and this is fine - no smell. Although the kitchen sink also sometimes smells a bit, but not sure if this is related.

Finally, it may also be useful to mention that when ever the taps/shower are switched off there is quite a loud bang from the pipes, which is most audible when downstairs. Again, not sure if this is related.

We are planning to have the bathrooms completely re-done next year, but we have our family coming to stay for Christmas, so if there is a quick (DIY-novice friendly!) way of tackling this problem now, then that would be great!

Many thanks for your help.

Does the soil pipe terminate in this upper bathroom with a dergo valve (air admittance valve) or does the stack terminate outside? If there is a dergo valve it might not be reseating properly.

Is there a basin or shower in this room that hasn't been used in a while? The water could have evapourated from the trap, leading to fowl drain smells entering the room.

Thanks Leakydave,

This is the highest toilet in the house, but not sure if the soil pipe terminates inside (with an AAV), or outside - what should I look for to work this out?

There is a bath in this room - which we use every night. There is also a B-day and a shower, but we dont use either, we only occassionally run water through them to try and keep the drains fresh.

Whats the 'trap', could I check to see if water has evaporated from it?

Many thanks again for your swift response and help!!

The water trap under bidet and basin to hold water to stop air coming into the room. Sniff the plug hole of bidet and basin... anything?

Does your soil stack stick up through the roof, up past the side of the roof, or can you not see it? Look at the route of the 4" soil pipe from the upper loo. Is there a boxed in section that finishes at about waist height?

Thanks again Leakydave

So is the trap the same as the u-bend pipe under the sink and bidet - forgive the lay-speak!

Am at work at the moment - but will give them a sniff tonight, however, Ive never really noticed a particular pong coming from them specifically, more of a general whiff within the whole room.

Im pretty sure there is a big fat pipe coming down the side of the house, which I guess is the soil pipe, but not sure from memory whether it continues up to the roof line, or whether it snakes into the wall and thus into the bathroom, i think it goes into the wall, but will also check this evening.

Certainly dont recall seeing any boxed section around the pipe coming from the loo - i think it disappears straight from under the loo into the wall, or possibly down into the floor.

Will check all the above tonight and get back to you, but if any of the above gives you any more ideas, I would be very very grateful.

Many thanks again,

Try pulling the side panel off the bath; you might find the source of the smell - a leaking pipe or the missing air admittance valve, which will look like a plastic mushroom. We had one under the bath and it stank; the flap had got stuck allowing foul air from the sewer to enter the bathroom.

Thanks RigidRaider

I will also try and look under the bath tonight as well. How big would the AAV be? The bath is not that big and is surrounded by screwed in wooden panels, could an AAV sit under there, would it get enough air-flow to work and would that be the AAV for the soil pipe - or does the bath need its own AAV?

Thanks again guys - really appreciate all your help!

The AAV should be sited higher than any other waste outlet or spill over level... so higher than bath, cistern, basin or bidet.

Once again - many thanks for your help.

I dont recall seeing anything higher than the toilet cistern, but the toilet does sit a little bit away from the wall, which I always presumed was due to a slightly sloping wall, but maybe the AAV is tucked in just behind the cistern - will have a look. Could it be within the cistern itself...?

If I dont find one, then I guess my soil pipe must vent outside. But in which case, how might the sulphury smell be getting into the room - and which seems to be sucked out (temporarily) when we flush the loo?

Happy to check or poke whatever you think might help diagnose the problem!

Cheers

In our last house we found one in a box between the bath and the wall, so it was only just above the height of the WC. It was a grey plastic cover about the size of a dinner plate, looking like a ship's ventilator sitting on top of a length of standard soil pipe. It wasn't worth trying to revive the flap that is supposed to close when air pressure inside the pipe increases so we just bought a new one.

Afternoon guys, made it home and have checked things out a bit!

Firstly, no notable smell from the sink, bath, bidet or shower plugs. Although my wife had 'used' the bathroom earlier in the day, so that might have sucked the worst of the smell away, although there was still a general whiff in the room.

Secondly, no sign of an internal AAV - the soil pipe goes straight from the toilet and through the wall.

Thirdly, when looking at the soil pipe from the outside, it seems that the pipe from the toilet joins the external pipe - which then carries on to the roof line and gutter. Its hard to see what happens to it then, given the angle of the roof, but i think it just stops, there doesnt appear to be any venting.

However, just by where the external soil pipe appears from the outside wall (alongside where the toilet is positioned on the inside), there is a much smaller pipe sticking vertically up and out of the soil pipe, before it meets the main vertical soil pipe (which other pipes drain into - such as the soil pipes form other toilets lower down in the house).

Could this relatively small vertical pipe be the air vent for the soil pipe system??

If so, it does appear to be blocked (although its hard to tell from ground level), but how else could the general smell, which is sometimes sulphury, sometimes just a little drain-like and mildly stinky, be getting into the room?

Thanks again everyone for your help trying to solve this puzzle!

Photo needed!