Bath trap gurgles

1 Feb 2007
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United Kingdom

I’ve just installed a new bathroom but when emptying the sink the bath trap gurgles. The sink, shower & bath are all on the same run to the soil stack.

I've installed an air admittance valve under the sink, this has reduced the gurgling but not stopped it completely.

The shower trap also use to gurgle but I've installed a HepVo valve (water less trap) on the shower tray so this no longer gurgles or back fills.

The old bathroom did not have a shower but the bath was (and is) slow in draining. Any ideas what is causing this or how to resolve it? Do you think my stack is part blocked?

Thanks for your help
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You should have run each appliance waste separately to the soil stack. Failing that, the common section must be large enough to take the flows without causing syphonage (gurgling to you), probably 50mm size. Also the pipe run should be mainly horizontal and direct with few bends. How is your waste arrangement?
Not as good as it used to be I'll bet, the binmen only come once a fortnight now dont they. :)
sooey said:
Not as good as it used to be I'll bet, the binmen only come once a fortnight now dont they. :)

Not like that like this.

chrishutt said......
How is your waste arrangement?

Not as good now its once a fortnight.........LOL

Its all about timing :LOL:
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You've missed your vocation there,you could be the new bernard manning, that fellah you used to work for said you were a comedian as well. :LOL:
All the pipe work is 40mm and mainly horizontal. Its in a H shape as I've tried to draw below. Ignore the dots they are an attempt to space the lines out


Its all under the floor now, I might try and fit an anti siphon valve under the bath but its going to be tight

So how are the T pieces oriented, where the shower, bath and basin wastes join? Many make the error of using the swept branch as the outlet, resulting in flows from one branch being sent back up the other branch.

"Horizontal" pipework still needs to have a reasonable fall, and the common section after the bath joins should be 50mm. I think you ought to think about biting the bullet and redoing the waste pipework under the floor.

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