The term “construction” when applied to plumbing, means placing all pipes in a new house without making the connections. Contractors usually do the building plumbing while the house is in the structure stage because that is when it is easier to place the pipes through the walls and floors. The home builder can save you a lot of headaches by making a diagram of the water supply and drainage systems, and check them with a certified plumber to make sure there are no code violations before installing.
The water system
The drainage system