Foul water dranage slope

[Fastjedi]

Working back from an existing inspection chamber to floor level via about 2m of pipe into a rest bend. The potential slope between the two points is circa 20 degrees. Should I
a) Run the pipe at 20 degrees to the rest bend at floor level
b) Run the pipe at 2.5 - 5 degrees with the rest bend below floor level + a vertical pipe to floor level

I am guessing (b) is the right answer as the rest bend is 87.5 deg and won't work into a 20 degree slope

Regards,
Ian

[Tony McC]

B would be ok over a short run such as this. Over longer runs, we'd normally use a slow bend at each end of the run - one bend connected to the IC; one to the RB, and a sloping pipe between the two.