I need to connect new toilet drain to existing exclusive drain ( 110mm pvc) and hence the need for an inspection chamber. The problem is the proximity to the wall wont allow it. An alternative is to connect at a shared 160mm drain a little further away but still on my property. My question is Am I allowed to break into this shared drain without permission and is there on the market an inspection chamber that allows a 110 inlet into a 160 chamber?