Hugo Nebula wrote:

From the chaotic regions of the Cryptosphere, Bob Minchin
wrote on Thu, 31 Jul 2003 22:13:02 +0100:


The Natural Philosopher wrote:


which is 1:22


Maybe this is too steep but how do you avoid using 2.5 degrees when the fitting
all come like this?


The gradient for _above-ground_ WC branches are between 18mm-90mm per
metre, which works out to 1:55 to 1:11, which works out to between
1.03° - 5.14°. So 2.5° is pretty much slap-bang in the middle.

Rest of the world 1, Natural Philosopher 0.


"A minimum size 100mm branch pipe may be used for a maximum of 8 WC's or
a length not exceeding 15m, gradient should be between 9mm and 90mm per
meter run" Building regs 2000 edition.

From building regs. So min fall is 1:100 roughly.

Since this is a macerator replacement, he will want to work as near flat
as possible.


The steeper gradients you quote are for washbasins and urinals and baths
on smaller diameter pipes.

External falls depend on anticipated flow rate - i.e. number of bogs
connected, and may be in large diamter pipe as low as 1:180. though
1:40- 1:80 is optimum. 1:60 is a good working figure.