New Sink Waste Coming Out of Bath Plug Hole?

[fosbie]

I'm planning on moving my sink in the bathroom to be near the bath and I want to connect the sink waste to the bath waste to reuse the same outlet through the wall for both. I'm worried that if I do that, when I pull the sink plug out, some of the water will wash up into the bath through the plug hole. Is this likely to happen? If so, what can I do about it?
Thanks.

 

[Richard C]

That’s very unlikely unless the bath waste leading to th stack connection is blocked; what you will get is siphoning of the water from the sink trap every time you empty the bath &, less likely, siphoning the bath trap when you run water down the sink; this causses lots of gurgling noises & smells.

The solution is to fit an automatic vent (AAAV) or anti-siphon trap to the sink waste but separate stack connections for each appliance are always preferred.

 

[fosbie]

Great, thanks for that. Should I also get an AAAV for the bath?

 

[Richard C]

Fiting one to the sink waste should be enough to prevent problems; try it first & take it from there.