in2minds wrote:

I will be moving various bits of soil piping around and have drawn a
blank on fall rates. From a look, old cast iron pipes look to have a
generally steeper fall than modern (smooth) plastic piping [which
makes sense].


I looked this up the other day and found reference to it being from 1:40
to 1:80


I had 1:60 to 1:110 s being in te range for outside work.

I'd say that 1:60 lies within all our estimates,so should be adopted.

LJ