Soil pipe - back air flow??

[krl*****]

Some advice please on a problem that has recently developed.

First a description of the system. All of the waste plumbing for the ensuite (shower and sink) and bathroom (toilet, bath and sink) all run to a single boxed in inernal soil pipe.

When we empty the bath there are air bubbles comming up the toilet, now when we flush the toilet there are air bubbles comming up the ensuite shower.

Any ideas on why and what we can do to solve the problem?

 

[Nige F]

Hi, Could be that the drains are blocked outside...lift a manhole or 2 and see..In my experience this is possible, but others have disagreed in the past..It`s your call.