Layout of Construction Drawings 147
6.6 PLUMBING DRAWINGS.
Plumbing drawings provide all pertinent information on the design of the plumbing system for a project,
including line sizes and location, fixture location, isolation valves, storage-tank capacities, hot-water-
heater capacities and locations, and drain locations and routing. Plumbing systems involve two major
components, water supply and drainage. Water is supplied under pressure through pipes to plumbing
fixtures. Drainage works by gravity: Drain pipes must slope downward. Vent pipes are required. A plumb-
ing floor plan will typically show the location and type of plumbing fixtures, as well as the route pipes will
be run (overhead or through walls) for potable water, drainage, waste, and vents. Plumbing drawings
are usually numbered beginning with “P,” as in P-1, P-2, etc.
Figure 6.18 Schematic diagram for a refrigerant-piping detail for air conditioning.