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How to Choose the Right Plumbing Pipe

4/2/21
Grainger Editorial Staff

It's important to choose the right pipe for any remodel, renovation or repair job. There's no one-size-fits-all solution. Many types of plumbing pipe are widely used today, and each has advantages and disadvantages in different applications. Among the most popular choices for plumbing pipe today are copper, PVC and PEX pipe. 

To figure out what kind of pipe you need, start by thinking of where the pipe fits into the building's plumbing systems. There are two basic plumbing systems in a building:

  • The water distribution system, which delivers unheated and heated water throughout the building.
  • The drain, waste and vent (DWV) system, which removes water, wastes and gas from the building.

For each of these systems, there are different materials of choice today, which are listed in the chart below. 

Plumbing System Pipe Materials of Choice
Drain, Waste and Vent (DWV) Systems PVC pipe, ABS pipe and copper pipe rated for non-pressure drainage applications
Water Distribution Systems Copper pipe, PEX pipe, CPVC pipe, PVC pipe (unheated water only) rated for low pressure applications

Pipe Choice for Drain, Waste and Vent (DWV) Systems

For the DWV system, the materials of choice today are PVC pipe and ABS pipe. These rigid plastic materials are favored because they're inexpensive, lightweight and not subject to corrosion. PVC and ABS have similar characteristics, but ABS is usually black while PVC is usually white. For DWV applications, pipes that are not rated for pressure are often used.

Historically, other types of pipe have been used for DWV systems, most notably cast iron because of its crush strength, but today these materials are used less frequently because plastic pipes are cheaper, easier to work with and can last as long or longer.

Pipe Choice for Water Distribution Systems

Copper pipe has been a standard choice in water distribution systems for decades because of its light weight and ability to resist corrosion. However, the cost of copper has risen dramatically over the years, and professionals have looked for alternate materials.

What about PVC? It's one of the most common types of pipe in general plumbing systems, but PVC is not able handle water at the high temperatures that water heaters can produce. PVC is generally not approved for temperatures above 140° F. Because of this limitation, there are usually building-code restrictions on where it can be used. One place that you'll commonly see PVC is leading away from drains into the DWV system. 

Among the first plastics to be widely used to distribute heated water in homes and commercial applications was CPVC, which was introduced during the 1960s. CPVC is similar to PVC, but the addition of chlorine to the structure of the plastic makes the material suitable for higher temperatures. CPVC can typically be used in the same places copper pipe is used.

In the 1980s, PEX pipe was introduced to the U.S. market. Unlike CPVC, PVC and ABS, which are all rigid, PEX is a flexible plastic. This means it can be accommodate wide-radius turns without a joint. It's particularly handy for retrofits or remodels that involve running new pipe through ceilings and floors.

PEX pipe also allows unconventional water delivery system design. Traditional rigid plastic or metallic pipes typically use a trunk-and-branch design in which a larger-diameter trunk pipe distributes water throughout the building, with short, smaller lines branching off to feed each fixture. PEX can be installed the same way, but it can also be installed using a manifold design, in which longer, small lines run directly between each fixture and a single manifold, usually located near the water main. Any of these individual lines can be shut off at the manifold if necessary, and the system also usually delivers hot water faster, and it can deliver water at higher pressure when there are fewer sharp turns. 

For these reasons, PEX has become an extremely popular choice for water delivery systems, though copper is also still used, as is CPVC.

Choosing Between Copper, PEX and CPVC for Water Distribution

The table below compares some of the advantages and disadvantages of PEX, CPVC and copper plumbing pipe for water distribution systems.

Type of Pipe Advantages Disadvantages
Copper Pipe
  • Time-tested, has been widely used since the 1940s
  • Can withstand exposure to sunlight
  • High cost
  • Can develop pinholes in areas with acidic water
  • Loses heat more quickly than PEX or CPVC
PEX Pipe
  • Requires fewer fittings because of material flexibility
  • Relatively quick and simple to install
  • Can be used with a manifold design
  • Damaged rapidly by exposure to sunlight
  • Installation requires special tools
CPVC Pipe
  • More time-tested than PEX, has been widely used since the 1970s
  • Damaged by exposure to sunlight
  • Installation involves a glue that requires good ventilation and respiratory protection

What About Other Pipe Materials?

While PVC, CPVC, ABS, PEX and copper pipe are the most widely used choices for installation and repairs in homes today, it's useful to understand the characteristics of some of the other pipe materials you may encounter, especially when working on older construction.

Type of Pipe Characteristics Where You'll Find It
Brass Pipe
  • A less-common alternative to copper with similar corrosion-resisting characteristics
  • Historically, often contained lead to make the material easy to machine and join
  • Available today in lead-free alloys that can carry drinking water
  • Frequently used for waste lines as well as for supply lines for hot or cold drinking water in fountains, bathrooms and kitchens.
Galvanized Steel Pipe
  • Widely used in homes before the 1970s
  • Susceptible to corrosion, despite being coated with zinc, which was thought to reduce corrosion 
  • Often used to carry wastewater or sewage indoors or outdoors 
  • Formerly used for water distribution in homes where copper or PEX would likely be used today 
Cast Iron Pipe
  • Extremely heavy and long-lasting
  • Susceptible to corrosion
  • Historically, used for moving water into and out of homes, where today builders would be more likely to use plastic pipes, such as PVC or ABS, that do not corrode and are lightweight and easy to work with
Lead Pipe
  • Once popular because of its durability and malleability
  • Prohibited by many cities in the U.S. by the 1920s
  • Sometimes found in service lines and in old buildings, though most old lead pipe has already been replaced

Finally, whether you're repairing old pipes or installing new plumbing, it's important to consult local building codes to make sure you're choosing materials that are compliant in your area.

Frequently Asked Questions

Q: What's the difference between schedule 40 PVC and schedule 80 PVC?

A: "Schedule 40" and "schedule 80" refer to different standards developed by ASTM International. These are the main differences between schedule 80 PVC and schedule 40 PVC: 

  • Schedule 80 PVC is usually dark gray, unlike schedule 40 PVC, which is usually white.
  • Schedule 80 PVC has thicker walls, which means it can be rated for the higher pressure applications often found in industrial or chemical facilities. Some schedule 40 PVC pipes are rated for pressure, while others are designed for use only in non-pressure applications in DWV systems.
  • Schedule 80 PVC has a smaller inside diameter and slightly restricted flow compared to schedule 40 PVC of the same size. This is because the outside diameters are the same, but the walls are thicker for schedule 80.
  • Schedule 80 PVC is heavier and costs more to produce and transport than schedule 40.

Q: What's the pressure rating for PVC pipe?

A: In general, the pressure rating for PVC pipe depends on the diameter of the pipe, the operating temperature and whether the pipe is the standard schedule 40 PVC or the thicker-walled schedule 80 PVC, which is usually dark gray. The pressure rating goes down as the pipe diameter gets larger and as the operating temperature get warmer. 

The information contained in this article is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This article is not a substitute for review of current applicable government regulations, industry standards, or other standards specific to your business and/or activities and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.

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