Bathroom waste pipes to sewer

[checkmate]

Hi all

Looking to refit my bathroom and had one question.

Currently I have one pipe for sink, one for bath tub and obviously toilet waste, can I merge shower and sink to one then both connected to sewer pipe?

Reason is my builder when I did extension didnt install properly in garden and he has connected sink and bath waste water to rainwater pipe!! And at times it overflows and leaks to decking

Thanks in advance

 

[Jadele]

you can the only issue is that sometimes if not done right you can end up with the sink water on release of a full bowl bubbling up the shower. Its just about where the connection is and the joints you use. The further away from the shower trap the joint is the less likely this is to happen. Its not ideal but its not impossible for it to work fine.