The Natural Philosopher wrote

Paul wrote:

We are thinking of re-arranging our bathroom layout which will mean moving
the toilet onto another wall, this will mean the waste pipe being extended
by about ten feet and also turning a corner. Will there be a problem if we
do this, looking around other houses they seem to have the toilet next to
the stack so the pipe work is as short as possible.



Yes, you may well have a problem, since there needs to be quite a fall
on a soil pipe to ensure the turds get sped on their way.

Let's just clear this up. This work will need to comply with the Building Regs
and for a branch pipe of 110mm dia with one WC, the Regs require 18mm fall per
metre run. So if the WC will be 3m away from the stack there will need to be
min 54mm fall from the invert of the pan outlet to the invert of the branch
connection on the stack pipe. If this can't be achieved it will be necessary to
either raise the pan or lower the branch connection to the stack. Remember
modern WC pans have horizontal outlets, which might help.

Peter