Calculating drainage fall and gradients

Drainage Pipework

Gradients between 1 in 40 to 1 in 110 will normally give adequate flow velocities. If the gradient is not steep enough i.e. less than 1 in 110, then the pipe could block if the solids slow down and become stranded.

All above and below ground horizontal drainage pipes should be laid to an adequate gradient. A gradient of 1 in 80 is suitable for commencing calculations for pipe schemes.

The fall or rise in a pipe may be defined as the vertical amount by which the pipe drops or rises over a given distance. The distance can be between sections of pipe or between manholes.

A gradient may be defined as fall divided by distance.

How we can help?

If you have issues with blocked drains, a soakaway or drainage field that has failed contact us at Tekneka Ltd onĀ  01772 846193 / 07968 143756 or fill in the contact form