can i change existing downpipe to a soil stack or would a long connection to an existing soil stack be better

[zachmbutcher]

i'm planning an en-suite in the bedroom beside the family bathroom (both on first floor). The existing soil stack is outside and approximately 2.5-3 meters an existing gutter downpipe and where new toilet would come out of the wall.

The house is 1938 and i assume that the existing rain guttering connects below ground to the toilet waste and runs of to a combined sewer - would need to check this to be sure.

My question is would it be best to or can i ...

a) Have a long soil pipe running along the back wall and joining the existing stack (not particularly attractive given the length along the wall)
b) Change the existing downpipe to a new soil stack and then boss in the guttering to the new stack? - a friend suggested Building Regs would want a whole new underground sewer pipe from the toilet to main drain in street.

 

[Hugh Jaleak]

Rainwater will still need to be kept separate above ground, other the rainwater pipework will act as a vent for the soil stack.

If the existing rainwater downpipe goes into a combined sewer, then this should be ok to connect a new stack into to serve the proposed en suite. You would then also need to provided a Trapped Gulley at ground level for the rainwater downpipe to discharge into.

If not, then a connection into the existing stack may be your only practical option.

Building Control will accept any suitable method that complies with the Regs, a new connection into the main sewer in the street would only be required if there were no other options for getting a gravity sewer from new stack position to an existing foul or combined sewer on the premises.