What Size PVC Pipe Should Be Used to Plumb a House?

Standards

• Generally, each local or state jurisdiction has requirements for all types of pipes used to plumb a home. These are compiled by the American Society for Testing and Materials, or ASTM International. ASTM International creates standards for construction and remodeling of homes, which local and state jurisdictions, pipe manufacturers, and associations such as the Plumbing-Heating-Cooling Contractors Association voluntarily follow to ensure safe and effective plumbing.

PSI

• Pounds per square inch, or PSI, is what is used to set standards for maximum water or fluid pressure allowed to move through PVC pipes. In many homes, the water pressure is reduced using a water pressure regulator to ensure no damage is caused to pipes installed in the home. Generally, water systems in homes run between 55 and 65 PSI. To determine the PSI in a home, call the relevant public water company or use a pressure gauge to measure the water pressure.

Schedule

• PVC pipes are also rated by the pipe’s density. The higher the density of the pipe, the higher the water pressure the pipe can withstand. Home plumbing systems generally require schedule 40 PVC pipes. Other applications such as industrial and commercial plumbing systems may require schedule 80 or 120 PVC pipes.

Size

• For water distribution systems, the size of PVC pipe generally runs from ½- to 1 ¼-inches in diameter. The main pipeline from the street is between 3/4- and 1-inch in diameter, and the supply lines in the home are ¾-inch in diameter. Individual pipes for fixtures such as sinks, showers and other connections are generally ½-inch in diameter. Water pressure decreases for PVC pipes that rise above the water supply line, so the second and third story of a house may require larger pipe diameters, according to Don Vandervort's HomeTips.com.

Considerations

• Consider all aspects of plumbing before selecting PVC pipe sizes. These considerations should include the water pressure, schedule, the size of the home and the local jurisdiction’s plumbing codes. Along with the size of the PVC pipes, some jurisdictions specify what primer and solvent can be used to weld PVC pipes -- for inspection purposes and to protect the environment.