We are wanting to install a downstairs loo. The loo's exterior outlet will be 1m from an existing 100mm diametre unvented drain which runs directly into the main vented drain 1m away. The kitchen sink, washing machine and loo basin will also drain into this existing drain.
As far as I can see there are no problems with the fall which is 380mm over the two metre distance.
Should it be ok to drain the loo, sink, washing machine and loo basin into this existing drain without venting it - considering its running for only 1m to a main drain with soil stack vent?
I hope this makes sense!
