In Reply to: WASTE/SEWER Ideal Fall posted by Rob Woollacott on December 03, 1997 at 19:07:43:
: I would like to know the ideal fall for laying the following;
: 1. A main sewer run in 100mm upvc from house to septic tank, approximately 12 metres.
: 2. Main waste run under floor of a pole frame home from vent pipe to start of sewer run approximately 13 metres in 80 mm upvc.
The ratio 1:40 is good fall (2.5 degrees). 1:60 is your minimum fall. So for the 12 metre run, 300mm fall would be excellent. Same for both the 100 & 80mm pipes.