The pipes in any home plumbing system are divided into two major parts. Contrary to popular belief, neither is too complicated for the average householder to understand. From the descriptions given in this page and by simply tracing the piping in your home, you should be able to determine the specific purpose of each pipe.

The first division you will be concerned with is the network of pipes which brings water into the house and to the various fixtures from either a municipal water main or a pump. This is called the water supply system. The network of pipes which drains off water and other kinds of waste into a sewer or cesspool is known as the drainage system.

Water in the supply system is fed to the various fixtures by pressure, which insures its flow, and is controlled by a series of valves, such as faucets and turn-off cocks. The drainage system takes advantage of gravity to remove waste.

Although these two piping systems and the fixtures will be discussed as separate units, it must be remembered that none of them can work properly unless they all do. To give satisfactory service, supply, fixtures, and drainage facilities must be adequate and installed correctly; all three must operate as a unit at all times and under all conditions.

For example, if the water supply pipes fail to deliver an adequate flow of water at a proper pressure, fixtures cannot possibly function as they should; if fixtures and the pipes leading directly to and from them are not installed correctly, their efficiency will be impaired and the drainage system will either fail to draw off the waste or else may cause a backflow of waste into an outlet or water line.

Local codes

In most localities, water is supplied by the municipality. If this is the case where you live, you will find that there are various laws, ordinances, and regulations pertaining to the distribution of water supplies which must be adhered to. Before attempting any plumbing work on your own, make sure you will not be violating any rule or regulation laid down by local authorities. One of the most common of these is the requirement that all connections to the civil water supply sustem must be made by a licensed professional plumber.

Complying with this regulation is a safeguard to both you, as the consumer, and to the purity of the municipal water system as a whole. Faulty installation at this initial point may cause costly leakage or contamination. Make your choice of professional plumbers a careful one. Inquiries as to the quality of work done by a plumber may save you countless dollars and much inconvenience.

Once hired, the plumber should be made to understand that all installations must meet local requirements and must be able to pass tests of local plumbing inspectors. Remember to have a corporation cock installed at the street main, if required, and a curb cock installed outside the house to enable you to cut off your water supply if necessary.

Good plumbing practice

A general set of principles which can be used to guide you is found in the Recommended Minimum Requirements for Plumbing developed by the Bureau of Standards, U.S. Department of Commerce (see for updates). These basic plumbing principles were written to meet the minimum sanitary requirements for all parts of the country, after due consideration of differences in climate, building codes, and methods of sewage disposal.

  1. All premises intended for human habitation or occupancy shall be provided with a supply of pure and wholesome water, neither connected with unsafe water supplies nor cross connected through plumbing fixtures to the drainage system. If such premises abut on a street in which there is a public sewer, they shall have a connection, if possible, a separate connection, with the sewer.
  2. Buildings in which water closets and other plumbing fixtures exist shall be provided with a supply of water adequate in volume and pressure for flushing purposes by pipes of sufficient size to supply such water without reducing pressure at other fixtures.
  3. Plumbing systems shall be maintained in a sanitary condition and will be designed and constructed to guard against fouling and clogging, but with adequate and accessible cleanouts in case, such stoppages should occur.
  4. Plumbing fixtures shall be made of smooth, non-absorbent materials, shall be free from concealed fouling surfaces, and shall be set free of enclosures, with each fixture or combination fixture provided with a separate, accessible, self-scouring, reliable, water-seal trap placed as near the fixture as possible.
  5. Drainage system piping shall be so designed and constructed as to be proof for a reasonable life of the building against leakage of water or drain air due to defective materials, imperfect connections, corrosion, settlements or vibration of the ground or building, temperature changes, freezing, or other causes.
  6. The plumbing system shall be subject to a water- or air-pressure test and to a final air-pressure test in such a manner as to disclose all leaks and imperfections in the work.
  7. House drainage systems shall be so designed that there will be an adequate circulation of air in all pipes and no danger of siphoning, aspiration, or forcing of trap seals under conditions of ordinary use. The soil stack shall extend full size upward through the roof and have a free opening with no danger of clogging from frost or roof water draining into it or of any air from it passing to any window.
  8. If water closets or other fixtures exist in buildings where no sewer is within a reasonable distance, suitable provision shall be made for disposing of house sewage by some method of sewage treatment and disposal satisfactory to the health authority having jurisdiction. Where backflow of sewage is possible, provision should be made to prevent its overflow in the building.

With these basic principles in mind, a proper plumbing system can be installed which will safeguard the health of your family. But there are several physical safeguards in the actual installing of a system. For example, though it is accepted that the main should be of a size adequate to supply sufficient water at all times, that main should be run as straight as possible to avoid frictional losses, and should be laid on a level bed of soft, rock-free dirt so that jagged or sharp cornered stones will not eventually cut into it.

All outside water mains should be provided with a “gooseneck.” This is nothing more than an additional kink or bend placed in the pipe in such a manner as to allow for expansion and contraction so that connections will not break and leak. The gooseneck is usually placed near the main and close to the corporation cock, so that all vibration, settlement, expansion and contraction will act to tighten the cock joint rather than loosen it.

Where the main runs through the foundation wall, it should be protected with a sleeve, usually of iron pipe, which does not touch the main itself. Made large enough to allow for expansion, this sleeve protects the main from contact with corrosive elements in concrete and also keeps minor physical changes from either straining the wall or the main.

Once the water main has been installed and local regulations met, it is entirely possible that the remaining interior piping can be installed by the owner himself. But before actually beginning installing and connecting pipe and fixtures, survey the area, whether kitchen or bathroom, carefully and plan out where each fixture is to be placed, what clearance you must allow, how the existing piping can be utilized, and what new piping will be necessary. The general principles and details of sketching a layout will be described in the pages that follow.