Some good sites that offer plumbing schematics include PoolCenter.com and Winnebagoind.com. A plumbing schematic is a simple diagram that illustrates the vent piping, drains, pipe fittings and pipes in the plumbing system.
As of 2015, Winnebagoind.com offers plumbing diagrams from 1999 to 2015. Users can search for plumbing schematics by year. The site also offers a plumbing parts identification list to visitors. PoolCenter.com provides a collection of plumbing schematics for pools to help homeowners understand how vacuum and pressure work in pumping water from the pool and back to the pool respectively. Users select the right diagram based on the number of valves their pools have.