Hi.
I'm after some guidance on how a drainage system is laid out. I am about to fit some new kitchen units for my mother in law and her existing kitchen sink waste runs into a round drain which is INSIDE the house. This drain seems to be linked directly to a square drain which is directly next to a square drain on the OUTSIDE of the wall.
The house is in North Wales and was thrown up in the 70s.
Previously if the outside drain has blocked, the inside drain has overflowed which is far from ideal!!
Can anyone tell me if I am able to seal the inside drain and simply put the 40mm waste through the wall into the outside drain (as you would normally expect to see) or if there is a reason the pipework is as it is?
Many thanks
