sm_jamieson wrote:
I've set out the main part of my drainage, being old clay to new
inspection chamber to rest bend and soil pipe etc, with the gradient
at 1 in 40. Two other connections on the chamber are to connect to two
roddable bottle gullies (one under outside tap, other for rain water
runoff - combined sewer). If these gullies are connected to the
chamber mainly with straight pipe, the gradient will be a lot steeper
than 1 in 40. Is this OK, or do I need to use some kind of rest bend
from the gully so that the main run of pipe from gully to chamber is
about 1 in 40 ?
snip

The '1 in 40' rule only applied to soil - rainwater can go at any angle,
but even soil drains are now no longer subject to the '1 in 40' rule.....the
idea was that ****, travelling at velocity, would splatter up the sides of
inspection chambers and the like, then when it set, it would build up into a
blockage, they now don't insist on this as slow moving turds cause blockages
themselves.