Smell in bathroom after use

[GoChasingWaterfalls]

For the last few days, whenever we use the bathroom sink, bath, or flush the loo, a horrible smell seems to come through the bath plug.

I've tried bicarb and vinegar, as well as drain cleaner, but it hasn't helped. The smell goes away after a couple of hours.

Any ideas what it could be? Thanks.

I’d be putting bleach and boiling water down. And maybe try one of those things that pulls hair out. Failing that, you need to check the sink u-bend and the bath pipe.

Soap, hair, dirt. Caustic soda (Mr Muscle or an own brand) will get rid. Bleach will also help. (not at the same time obvs!)

If all the cleaning methods don’t work, check for a leak. We have had a leak at the back of the toilet twice due to poor fitting which caused the bathroom to smell.

Get some Mr Muscle unblocker and leave it overnight.

This can sometimes happen if the water in the ubend is syphoned out. (eg the toilet flush creates vacuums strong enough to suck out the water in the bath ubend). It's a sign of poorly designed waste pipes, so wouldn't normally happen unless changes have been made.
If you suspect this, poor a pint of water down bath after using basin/toilet to replace the water seal. If smells stop, then that's probably what it is.

Well having conducted extensive research involving me sniffing and flushing a lot I think this is what is happening. As soon as I flush the loo the smell comes out of the bath plug hole.

But now I'm wondering why. We haven't made any changes, the bathroom was installed two years ago.

Could it be a leaky pipe that is doing it?

I'm going to have to cut through all the sealant on the bath panel and surrounding tiles to take a look aren't I?

We have this since having a new bathroom fitted. Cowboy builders didn't put a vent on the soil pipe. We have to clear the manhole once a week.

If you've changed nothing it could be because of a partially blocked soil pipe so when you flush the toilet the water completely fills the pipe and causes a vacuum behind it.

Not sure I'm really experienced enough to advise. I guess you first need to be sure that it is syphoning. It could gurgle as it's doing it. Also when the trap has emptied you'll be able to hear and smell the goings on in the waste pipes when you get close to the plug hole.

It's hard to know why this has become an issue now. Perhaps it was close to being a problem when installed, and now the pipes have become a little dirtier. Restriction sounds more likely to me than leaks.

The solution to this problem is to use some sort of air admittance device. You can buy traps with built in anti-syphoning devices. If there's a vacuum, it'll let in air, so maintaining the water seal. If you can find one that's similar to your bath trap, it's a simple swap. Macalpine (at Screwfix) appear to have some.
Or call a plumber.

Depending on pipe arrangement, using an anti-syphon trap on the sink instead could work.

As above fitting an air admittance valve or anti syphon trap is the usual solution.
It depends on the layout and accessibility of the waste pipes which is most suitable.

Showers are typically the first to show up siphoning problems because the trap is shallower.

Having had similar and being told the problem, here goes.

Pop outside tomorrow and take a look at your roof. Does the soil stack poke through the roof?

If no, then in your loft you will have a durgo valve. This is meant to open when you flush the toilet, use the sink, drain the bath/shower however they can seize up and when they seize, random stuff happens such a bizarre gurgles from the basin, a really slow draining bath or shower, a toilet flush that doesn’t have ‘oomph’.

Do not put bleach or those kinds of chemicals into shower traps, oddly it makes it worse but it’s fine to use them on sinks (yep, I don’t really get that either but hey ho). Even boiling water and soda crystals will bring niffs back with a vengeance.

In short, if you don’t have a soil stack you’ll need a plumber to get up to your loft to check your durgo value and if it’s seized (quite common) to either un-seize it or replace it.

We get this in our wash basin in the bathroom and kitchen sink. Washing powder and boiling water (a few times) always sorts it here.

So, sorry, pour washing powder down the plug hole and then wash it down with boiling water.