PLUMBING - Typical Plumbing System - PDF

The residential plumbing system is often taken for granted, but it is an important part of the structure.
A complete plumbing system provides an adequate supply of water and removes waste.

There are three principal parts :
  • Water Supply System.
  • Water and waste removal system.
  • Plumbing fixtures.
Water and Waste Removal
  • Used water and other wastes are carried to the sanitary sewer or septic tank through the waste removal system.
  • These pipes are isolated from the water supply system and must be sized for sufficient capacity, have the proper slope and venting, and have provisions for cleanouts.
  • Typically it is practical to drain as many of the fixtures as possible into a single main drain.
  • The drainage system is not under pressure and depends on gravity to carry the waste to the sewer.

  • The trap most commonly used with plumbing fixtures is the P-trap. The P-trap gets its name because of its general shape that of the letter P.
  • Traps are required because they prevent sewer gases from entering a building and causing serious illness or death.
  • The term trap seal refers to the water being held in the bent portion of a fixture trap. The trap seal forms a seal against the passage of sewer gases through the trap and into the building.

House Drain
  • A house drain is the pipe that receives all waste and water discharged by the soil stacks and water lines.
  • This house drain is laid from a point just outside the building foundation wall where it connects to the houses sewer, then through the wall, and either along or under the cellar floor to the point where connection with the soil stack is made.
  • Before laying this drain, determine its overall length and how much pitch to give it so that it will drain as it should.

  • A plumbing cleanout is a cleanout fitting with a removable plug that is found in a roughed in waste system. It is designed to help keep clear any type of debris that could cause any type of stoppage in the water drain lines.
  • Cleanouts are usually placed at the connection point between the sewer lines and the drain in where the base is located of a vertical stack and at all places were the pipe direction changes at 90 degrees.

  • To prevent the siphonage of trap seal in fixture traps and allow gravity flow of drainage, you must let atmospheric air from outside the building into the piping system to the outlet end of the trap. The air is supplied through pipes called VENTS. This air provides pressure on the outlet end of the seal equal to pressure on the inlet end.
  • Since the air supplied by the vent to the outlet end provides a pressure equal to that the inlet end of the trap, the trap seal cannot escape through siphonage.
  • All vents systems should be provided with a main vent or vent stack and a main soil and waste vent. A main vent may be defined as the principal artery of the venting system, and vent branches may be connected to the main vent and run undiminished in size as directly as possible from the building drain to the open air above the roof.
  • The term main soil and waste vent , or soil stack vent, refers to the portion of the stack extending above the highest fixture branch. This vents extends through the roof, actually it is an extension of the main soil and waste stack.

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