Greenhouse drain-pit calculator
Enter the run, slopes and pipe sizes in mm; the calculator returns the height of the pipe hole in the drain pit (drooggat) and draws a live long-section. The pipe invert (bottom) is continuous and carries the slope.
Drain run
Pipe
Ground & drain pit
Long-section (side view)
Water flows right → into the pit. Levels are relative to ground level at the pipe start.