TABLE OF CONTENTS In today's buildings, all occupancies must be provided with a supply of drinkable water that has enough volume and pressure to make it easily available. This refers to all plumbing components needed to supply the water safely, and all required to carry it safely away.
Plumbing systems are chiefly gravity-septic, well-septic, or meter-sewage. In gravity-septic systems, the supply water arrives from a stream or other surface source located at an elevation above the building and acquires its pressure from gravity, then its waste discharges into a septic/leaching field at least 100 ft downstream from the surface source. In well-septic systems, the supply water arrives from a dug or drilled well and acquires its pressure from a pump, then the waste discharges into the same kind of septic/leaching network as does a gravity system. In meter-sewage systems the supply water enters from a pressurized public main, then the waste drains into a public sewer system. Gravity-sewage, well-sewage, and meter-septic systems are also possible, but uncommon.
A building's plumbing system has three parts: supply (the piping that brings the water to its points of use), fixtures (point-of-use receptacles that receive the supply water and discharge the waterborne wastes), and waste (the piping and venting that convey the wastes and any associated gases from its points of use to outside the building). The essential component is the fixtures: without them there is no need for the others. The chief criteria for designing a plumbing system are...
