The Average Home PVC Plumbing Size

Building and Plumbing Codes

• Many jurisdictions enforce building and plumbing construction codes, which requires certain types and sizes of PVC pipes and fixtures. Many jurisdictions recognize standards set by ASTM International, which develops international standards for a variety of systems and materials used in residential and commercial construction.

General Information

• The size of the pipes generally depends on where in the plumbing system the pipe is located, and the flow rate of the location. Residential plumbing systems are broken down into zones. Each zone requires a different flow rate capacity, pipe size and type of PVC pipe used. The position of the pipes also requires a size-range to ensure pressure and flow-rates are effective. Lateral pipes, for example, will have a lower flow rate. Incoming water pipes versus outgoing drainage pipes also require different pipe sizes.

Sizes

• PVC pipe sizes are broken down categories. The Plastic Pipe and Fittings Association offers a general synopsis for pipe sizes and plumbing system types in diameters. Sizes and types depend on the size of the system. Water mains use 4- to 36-inch pipes. Drain, waste and vent pipes use PVC pipe sizes 1 ¼-inch to 12 inches. Cellular core sewer PVC pipes are 2 to 15 inches, and sewer lines are 4 to 15 inches. Drain pipes are 2 to 6 inches.

Fixtures

• Water supply pipes and drainage fixtures also have standard sizes enforced by each jurisdiction’s plumbing codes. Household fixtures, such as shower heads, bathtubs, dishwashers, washers, toilets and water tanks, require a minimum pipe size to ensure proper pressure and drainage. Pipe sizes for household fixtures generally range from 3/8 to 3 inches in diameter. The largest pipe size is for the toilet, which flushes water and waste at a higher velocity. Smaller pipes attach to fixtures, such as the sink in a lavatory, and the water heater tank that heats the water connected to the PVC pipes.