what drop do i need on long waste run ? Drainage and wastage systems and plumbing help, advice and answers

[czimmerl]

Hi i am putting an ensuite in, i intend to drop the waste through the floor and create a false ceiling in the corridor below that runs the length of the house. The ensuite will be at the front of the house and mains waste is at the back. The total run is 46ft or 12 meters.
Q1) how much drop over that distance do i need ?
Q2) and/or what is the calculation ?
Many thanks
Martin

[plumbbob]

The minimum fall for all internal waste pipes is 18mm per metre.

You must consider the diameter of pipe as this will be critical over this distance.

What were you thinking of using?