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What are the Different Types of Plumbing Pipe?

By C. Ausbrooks
Updated May 17, 2024
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The two major categories of plumping pipe are plastic and metal. Plastic pipes include polyvinyl chloride (PVC), chlorinated polyvinyl chlorine (CPVC), PEX pipe and PolyPipe®. Copper, stainless steel and galvanized steel are all types of metal plumbing pipe. Not all pipes are as useful or effective as others, and each type is used for a specific purpose in plumbing.

PVC pipe is a type of plastic plumbing pipe primarily used to transport high pressured water. It is available in several standard sizes, ranging from ½ inch (1.3 centimeters) to 4 inches (10.2 centimeters) in diameter. PVC pipe is only made to handle cold water, as hot water will cause the pipe to warp. It is generally white in color, though a few varieties are gray.

CPVC is PVC pipe that has received an extra chlorination. It comes in a distinctive yellow color, and can handle both hot and cold water. CPVC is more flexible with substantially thinner walls than PVC pipe, and has the same outer diameter as copper pipe, which increases it's range of uses.

PEX pipe, also known as cross linked polyethylene pipe, was first manufactured in the 1920s, but has become more popular in recent years. It shares the same outer diameter as copper, and can be used for both hot and cold water. However, PEX pipe has a much higher heat resistance than most other plumbing pipe, and is often used in water-based heating systems. It comes in a creamy white color, as well as red and blue which is used to denote hot and cold pipes respectively.

The final type of plastic plumbing pipe is PolyPipe®, a thick black pipe used to transport highly pressurized water, usually to and from the home. It is used almost exclusively outdoors, and is usually buried underground to prevent freezing. PolyPipe® is extremely rigid, and is rarely used for other purposes.

Copper is the most common type of plumbing pipe used in the home, although it is more expensive than plastic piping. Copper is especially resistant to corrosion, and can withstand high temperatures. Copper pipes come in three different sizes – type M, L, and K. Type M has very thin walls, while type L is of medium thickness, and type K is the thickest of the three.

Stainless steel pipe is less commonly used than other metal pipes, as it is more expensive and harder to find. It is primarily used in marine environments because it can withstand salt water, which would erode most other metal pipes. The price makes it less desirable for other applications, or in safer areas where a copper pipe would perform just as well.

Galvanized pipes have been used in homes for years, typically to carry water in and out of the house. The galvanized coating prevents rusting, and gives a dull gray appearance. Use of these heavy duty pipes is diminishing, as it is being replaced by PEX pipe, which is less expensive and just as durable. Galvanized pipes typically come in sizes between ½ inch (1.3 centimeters) and 2 inches (5.1 centimeters) in diameter.

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Discussion Comments

By anon319154 — On Feb 11, 2013

@Istria: I saw your question asking about the safety of Pex pipes. I can tell you from my experience that

Pex pipes have tested safe and do not leach any toxins into the water. These tests were run at an independent lab for me. However, you may not be able to trust your water supply and should test that. I do not have any information on CPVC. PEX however, was endorsed by my doctor.

By anon318486 — On Feb 07, 2013

What kind of pipe is generally used for grease interceptor drain lines?

By anon304560 — On Nov 20, 2012

Istria, from my research, no one really knows. I keep wondering the same thing. But the EPA has mandated all plumbing be lead free, so all the metal pipes and fittings now made are lead free. There are different types of PEX and only some of them are okay to use in chlorinated water (any system on city water). Also you cannot recycle PEX.

Giraffe Ears, you are very trusting of the regulatory bodies. They are not that strict. They have to have substantial evidence to change any type of regulation, which means it may be years after we know something is bad for us, before they actually regulate it.

If anyone finds a plumber that still does copper, let me know.

By GiraffeEars — On Jan 14, 2011

@ Istria- PEX and PVC plumbing pipe must meet a very stringent set of standards that speak to the safety, strength, and so on of the pipe. I am sure that the regulatory agencies that set these standards take things like lead, chemical, and heavy metal contamination into account.

By cougars — On Jan 11, 2011

@ Istria- I can answer your questions about the types of plumbing pipes and fittings that are LEED certifiable, but I cannot answer to the leeching of chemicals into the water that runs through them. Almost all types of plumbing pipes are able to gain LEED certification as long as they meet certain criteria. For exact criteria, you would want to contact the USGBC.

The plumbing you use can qualify as long as it is made from a certain amount of post-consumer recycled material, meets and exceeds standards for safety, uses as little energy as possible to produce, and is made from materials that are sourced within a certain radius. A number of pipe manufacturers that make pipe to meet LEED standards.

You should keep in mind though that the pipe alone will not make your home qualify for LEED certification. You will need to take into account the efficiency of your plumbing system, the total amount of pipe laid to complete your home system, the system's impact on the site, the ease of access of the system for repairs, and the overall cost comparison to a comparable conventional system.

By istria — On Jan 10, 2011

I think it is great that there are new options for plumbing pipes, but I have a few questions I hope people can answer. How environmentally friendly are the different types of pipes plumbers use for plumbing? I would also like to know if CPVC and PEX plumbing pipes leach toxins like other plastics. I have always wondered how safe it was to constantly bathe in the hot water pumped through these pipes when we are not supposed to drink from containers that contain these plastics (BPH etc,).

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