Lay down blueprints as to where you want the pipes to go
Nobody likes mixing up pipes especially, when it comes to mixing clean water and dirty water. Before you install the plumbing or repair the plumbing, trace the lines as to where the pipelines go and as to where they get their water. By knowing the origin and end of the pipelines, it would be easier to track down a leak and center in on the problem instead of overhauling the entire pipeline system just to get rid of one tiny leak. By also knowing the blueprints, you can also improve your line and conserve water. Thus, indirectly - save some money on water.