Principles of Plumbing Design
The plumbing system in your home is a complex network of pipes, fixtures and vents that carry freshwater in and wastewater out. It’s also a vital safety feature that protects against backflow of contaminated water and other dangers.
While every house has a slightly different setup, there are a few key principles that all plumbing systems must follow. These principles are based on basic laws of gravity and pressure. Understanding these principles can help you identify and troubleshoot common plumbing problems.
All buildings shall be supplied with a potable water supply of suitable quality for human consumption and adequate for the normal use and cleaning of all plumbing fixtures and devices. All plumbing pipes shall be well constructed, leak-proof and of durable material. All joints in piping shall be properly soldered or brazed and tightened to prevent leakage.
It is a principle of plumbing design that all fixtures, appliances and piping should be located so they can be easily cleaned or serviced. This includes accessible shut-off valves. It is important that these valves be labeled so they can be quickly turned off in an emergency.
A piping system that conveys both water and waste in a single conduit is called a drain-waste-vent (DWV) system. The DWV system includes all of the pipes in your home that transport both water and sewage. It also includes the venting system that ensures the proper flow of air throughout the plumbing system.
The piping in the DWV system should be designed with a slope or fall that will allow gravity to carry waste and sewage to the drainage system. The slope is called the grade of the pipe. It is important that the grading be correct to avoid blockages and other problems.
Key Principles of Plumbing Design
All plumbing fixtures and their associated parts must be of a type and size that will permit their safe and effective operation under all conditions of usage and cleaning. Fixtures should be so arranged that their piping will not be subject to the hazards of fire or explosion. All piping in the DWV system should have an adequate air gap to prevent stagnation of water.
Sewage and other liquid and solid wastes that discharge from a building’s plumbing fixtures, appliances, and devices shall not be deposited in any groundwater supply well or in any surface water body unless such deposits have first been rendered innocuous through some acceptable method of treatment.
Besides sloping, the plumbing system must be sized to accommodate the maximum possible usage. This will allow the system to handle peak demands without overflowing or causing other problems. The piping in the plumbing system should be well-ventilated to avoid trapping odors and to allow for easy maintenance.
All plumbing fixtures should be equipped with a self-scouring and reliable drain trap. All water closets and similar fixtures must be located in rooms or compartments that are properly lighted and ventilated. All plumbing drainage systems should be protected against backflow of sewage or other toxic materials. This protection can be achieved through the use of backflow preventers or by installing a negative pressure zone backflow preventer at all water supply valves in the building.