Anti syphon trap on bath and basin?

[hexdex]

Hi all.

As I'm getting into the bathroom renovation I've been thinking that maybe it would be a good idea to fit anti syphon traps as we often, though not always, suffered the wonderful gurgling from the sink in the previous suite whenever we emptied the bath. So is it good practice to fit anti syphon traps on bath AND basin, or just the basin in our case. All pipework underfloor is sound and will be used again, so it's just new traps.

Thanks.

 

[Newboy]

Gurgling from any trap is usually a sign of a poor installation and/or a partial blockage.

 

[dilalio]

Hi all.

As I'm getting into the bathroom renovation I've been thinking that maybe it would be a good idea to fit anti syphon traps as we often, though not always, suffered the wonderful gurgling from the sink in the previous suite whenever we emptied the bath. So is it good practice to fit anti syphon traps on bath AND basin, or just the basin in our case. All pipework underfloor is sound and will be used again, so it's just new traps.

Thanks.

It all depends how far you want to go...
Something we have to balance with customers all the time.

Ideally, the different fittings should all have their own waste runs to the stack, but with internal stacks that is often just not possible and wasn't done in the first place so, depending on your own setup, anti-vac trap on the basin can't hurt, but may not solve the gurgling.

 

[hexdex]

Yeah, it's a downstairs bathroom with the bath and basin waste joining under the wooden floor before disappearing down to the main sewer pipe. So do you think it's only worth trying on the sink as that's what suffers when the bath empties?

 

[dilalio]

Try it and see what results you get.
You could always fit hep20 waterless traps. Just do the basin and see what results you get before sealing up the bath. If you put in a concealed cistern for the wc with a back-to-wall pan and have boxing for the cistern you could put a stub stack in the boxing with an air-admittance valve at the top of the stub stack that would allow air in there.