Flamingo Workbench
https://www.freecadweb.org/wiki/Flamingo_Workbench
Tutorial
Connect 2 cisterns with a pipe - https://github.com/oddtopus/flamingo/blob/master/tutorials/tutorialPype2.pdf
OSE Notes - for plumbing, OSE has the Piping Workbench. This provides industry standard components. Flamingo does not have PVC components.