Gurgling from badly designed discharge pipe. Any way to lessen problems?

[The Bedwetter]

Any ideas as to what can be done to reduce the impact of induced syphonage in this situation?

One badly designed (too long) 40mm wastepipe is used for the bath, basin and kitchen-sink. Inevitably there is a good deal of gurgling when, say, the kitchen sink is drained as it ‘pulls’ noticeably on the bath-trap. I have tried fitting this type of trap to the bath but it makes negligible difference. Would fitting a P-trap with an anti-syphon attachment be worthwhile? I also have a 40mm AAV – maybe I should install that instead?



Thanks in advance for any advice.​

 

[Masood]

Put an anti-vac trap on the kitchen sink. You want to break the vacuum before it forms ideally...

 

[Nelson-]

an AAV in the kitchen sink cupboard would be my first attempt.

 

[The Bedwetter]

Thanks for the advice. Actually adding an AAV here is not going to be straightforward as the twin sink has its own pipework as its OD is not compatible with 40mm. It looks like I am going to have to rerun quite a lot of this if I am to get the AAV on the section between the sinks.

 

[Masood]

Actually adding an AAV here is not going to be straightforward as the twin sink has its own pipework as its OD is not compatible with 40mm.

McAlpine 40mm compression should be OK..