Black ABS hard pipe is typecially used for waste water in houses. I am not sure it is rated for use in drinking water. White PVC is safe for drinking water. I have also seen folks use black flexi (funny) pipe in aquariums. That is typcially used in sprinklers systems or irragation.
Yeah,I like black returns too.I'm useing "funny pipe" for a return manifold plumbed to a closed loop(external) pump.For sump returns,Loc-Line is black and threads into bulkheads.