: Would anyone out there know the formula to measure time required for a fixed amount of water (say 4L) to travel a set distance (say 20M) thru a plastic SW pipe 90mm at a gradient of say 1 in 80 please. Seems to me to be a simple way to get it right. Many thanks LenYes there are formulas for this and everything else relationg to piping systems BUT you have to consider FRICTION losses through fittings 90 Degree bends etc.
