I am an engineer by trade and a philosopher and thinker by choice.
Over the years, the art and science of plumbing has changed dramatically. From the first terra cotta pipes in about 1700 B.C. to the newest PEX pipe technology today, no building is complete without plumbing. If it weren't for plumbing and plumbing professionals, the urban sprawl that we have experienced today would not have been possible. And if it weren't for pipes, plumbing would not be possible either. In this article, I will discuss and compare the advantages and disadvantages of many of the pipe technologies that have existed or currently exist on the market for residential use.
Comparison of Properties for Common Pipe Materials
|Cast Iron||Copper (Type M) *||CPVC (Schedule 40)||PVC (Schedule 40)||PEX (Class A)|
Pressure Rating @ 73°F
Pressure Rating @ 180°F
Max Service Temp
Softening Point (Vicat Test)
Tensile Strength @ 180°F
3.8 Btu in /h ft² °F
19.2 Btu in /h ft² °F
1 Btu in /h ft² °F
1.1 Btu in /h ft² °F
3.2 Btu in /h ft² °F
0.11 Btu/lb °F
0.09 Btu/lb °F
0.2 Btu/lb °F
0.25 Btu/lb °F
0.55 Btu/lb °F
Note: Joining method and material will govern the pressure rating for copper. In this table, a 50-50 tin/lead solder is used because it is the weakest of all the common copper joining methods.
Cast Iron Pipe
In the 1960s, cast iron pipes were the most popular form of plumbing in residential construction. This pipe was cheap and relatively easy to install for its time. It was also noted for its strength and ability to withstand high pressures. At the time, this made it ideal for home installation. Unfortunately for cast iron, it had one major flaw. This pipe was prone to failure due to rusting. Most cast iron plumbing systems had at least one leak within 20 years of installation, but many homes had more than their fair share of plumbing problems. Cast iron pipes were also known to leave a metallic taste the water. This was due to the iron leaching into the water from the rusting of the pipe. Today, cast iron pipe is no longer used for residential plumbing because of its faults.
Copper is probably the most commonly used plumbing materials in the United States today. This plumbing material offers long term durability and stability yet is soft enough to resist shattering upon impact. It's so durable, in fact, that copper pipes can even be used outdoors in both above and underground setting. Another advantage of copper plumbing is its natural ability to resist the growth of bacteria. This is important because it helps to ensure that your water supply is clean and safe to use. And finally, copper has a very high melting point and is able to resist deformation. This means that during a house fire, the plumbing may remain intact and could possibly be reused.
Despite all the great things that copper has to offer, there are a few disadvantages. The first notable disadvantage is the fact the copper is expensive to purchase and install. Installation of this plumbing requires soldering equipment and the skills of a trained plumber. Copper pipes can also be subjected to major corrosion if the water it contains becomes too acidic. In addition to this, copper pipes can leave water with a slightly metallic taste.
Next to copper, PVC pipe is also one of the most common materials used for residential plumbing applications. PVC is great because it is an inert and stable material that resists corrosion. It is also a very cheap material that is quick and easy to install. A minimal amount of skills and tools are required to properly install PVC pipes in a home.
The main disadvantages to PVC pipe is that it is very brittle that can break or crack if miss-handled. This is especially true for properties located in cold climates. In addition to this, it can only be used indoors and is not intended for hot water distribution (it has a maximum service temperature of 140 degrees Fahrenheit). Because of this, care must be taken when installed near hot items such as furnaces or ovens.
CPVC stands for chlorinated polyvinyl chloride. This yellowish plastic polymer was invented to handle the higher temperatures that regular PVC could not. It also is slightly stronger than standard PVC. CPVC has a few advantages over copper as well. It is generally a stable compound and will not corrode as easily as copper pipes can. CPVC also requires about 25% less time to install than copper does (though it does require more bracing). However, it is not as easy to install as other plumbing materials such as PEX.
The disadvantages of CPVC include that it is brittle and it can't withstand very high temperatures like copper can. Another disadvantage to CPVC is its high thermal expansion coefficient. Because of this, CPVC may not be the best choice for climates that experience wide variations in temperature. Additionally, CPVC typically costs about twice as much as standard PVC does.
PEX is shorthand for "cross-linked polyethylene." This material is relatively new to the field of plumbing (only appearing in the USA about 20 years ago) and offers some clear advantages over other available materials. The first, and most notable, characteristic about this material is that it is flexible. The flexibility of the pipe allows installers to avoid many obstacles while also using less fittings. The speed of installation is also increased by the fact that the pipe fittings are generally of the compression type. And finally, PEX is very good at resisting the effects of freeze and thaw because of its flexibility.
However, there are some disadvantages to this material. Installation generally requires the use of extensive bracing and supports. If not done properly, the pipes can move within the walls when the water is turned on and off (water hammer). PEX cannot be used outdoors unless it has a UV blocking coating. PEX is also a softer material that rodents seem to enjoy chewing on. This can lead to a sudden and catastrophic loss of water pressure (and potential water damage) within a home.
Weighing the Pros and Cons of Different Materials
The overall consensus is this:
- Plastic pipes are the cheapest to purchase and install, however, they generally cannot be used outdoors and have relatively low service temperatures.
- Copper is the way to go if you need to deliver hot water or want something that this durable and long lasting.
- Today, many houses are being constructed using a combination of PEX and copper plumbing. This combines the ease of installation of PEX with the durability and strength of copper. This affords new homeowners the best combination of advantages that the residential plumbing industry has to offer.
Questions & Answers
Question: Can copper fittings be used with PVC pipe in residential dwellings?
Answer: It's usually preferred to stick to one material type when plumbing a home. However, it's not uncommon to see installations where you have a mixture of copper and PEX or copper and PVC pipes. For instance, it's very common to see copper used for the pressure lines and PVC (or ABS) to be used for the drain lines or to see copper used for anything outside of the home and PVC or PEX for the interior of the home. Another reason you may transition from copper to PVC is when you have a line that is going to be used to supply water to an irrigation system. Most irrigation systems utilize PVC and polyethylene pipes to supply water to plants and sprinkler heads.
Whenever making the transition between copper and PVC (or any two different materials), it's very important to use the proper fitting. For instance, you could solder on a threaded fitting to the end of a copper pipe that can then be tightened into a threaded PVC pipe.
James on June 30, 2020:
I would recommend to go for CPVC pipes, as CPVC is a more stable compound as compared to others, and it does not corrode easily. Along, with that these pipes also required just around 25% less time for installation, and are more stronger than PVS pipes, more importantly then can handle temperatures upto 200° Fahrenheit. However, it is not easy to install on your own, therefore I would recommend to hire a professional to do the job for you.
Kevin Hussey from Baton Rouge LA on May 10, 2015:
We had cast iron as a drain line in our kitchen and it failed. We had to jackhammer our floor and replace it with PVC. Insurance covered this. Downside is that they would only pay to repair the section that failed.... there is probably another 50ft (or more) of the cast iron in the slab that will fail at some point in the future.
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Christopher Wanamaker (author) from Arizona on November 19, 2014:
Lead is interesting as it was used in some of the earliest forms of plumbing. In fact, the word "plumbing" comes from the Latin word for Lead. I didn't include this material in the list because it it is rarely used today, if it all, due to the possibility of lead poisoning.
steven on November 19, 2014:
what about lead pipe ?
Ruby S. on March 04, 2014:
Very useful information particularly for people that are looking for different types of pipes. This will educate them what pipe should they choose.