Inline /Tee air admittance valve to prevent siphonage

3 Aug 2016
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United Kingdom
I am just fitting my bathroom and have the bath and sink running off the same 40mm waste pipe. (Not possible to run the separately)

The pipe runs Bath >> Sink >> Soil pipe.

I have this bath waste / trap

and I am worried about it being siphoned when the sink is drained (Is that likely?)

I was wondering about fitting a air admittance T such as this:

in between the bath and sink.

Does that sound sensible and should it reduce any risk of the bath trap being siphoned?
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The risk is more that emptying the bath will pull the basin trap.

Fit an basin trap with an incorporated AAV
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