PVC vs. CPVC: Understanding Which Pipe Is Best for Your Job

As contractors and managers, you’ve most likely utilized PVC and CPVC in various projects. There are a few differences between PVC and CPVC that are obvious just by seeing and holding them. However, there are even more differences between the two materials that will help you determine the correct applications for PVC and CPVC.

How PVC and CPVC Differ

The first difference between PVC and CPVC that everyone notices is the extra letter. If you’ve used PVC or CPVC for retrofitting or on a construction site, you know you cannot use these materials interchangeably. Once you understand what that “extra C” actually means, it becomes clear what the main difference between PVC and CPVC is and why they have different uses.

The Main Difference Between PVC and CPVC

PVC stands for polyvinyl chloride, which basically means that it is a combination of chlorine and carbon. This combination makes it a strong but flexible material that absorbs shock, never rusts or rots away, and is resistant to bacteria. For these reasons, it’s a seemingly ideal material to transport water.

On the other hand, that extra C in CPVC stands for chlorinated. If you’re paying attention, you realize that CPVC is actually chlorinated polyvinyl chloride. The increase of chlorine during manufacturing changes the material quite a bit, which is described more below. However, CPVC is still strong and particularly resistant to rust and bacteria, which means it continues to be a great choice for water transport.

Range of Temperature Tolerance

There is one disadvantage to using PVC and CPVC as an application for water—and that is PVC can only handle temperatures up to 140 F. Anything hotter than 140 degrees will melt the material. To give you a point of reference, the maximum temperature of hot-water heaters is usually between 120-140 F. Therefore, PVC can’t really be considered a safe material in indoor plumbing.

That’s where CPVC comes in. CPVC can handle temperatures up to 200 F, which is an increase of 60 degrees. Although this is still not the highest water-temperature tolerance in plumbing, it’s significantly better than PVC.

Differences in Pipe Strength

While the added chlorine in CPVC increases its heat tolerance, it also changes the strength of the material. Both materials are very strong, but CPVC is harder than PVC, which makes it more prone to breaking. CPVC is more brittle than PVC and can be warped or cracked more easily, but it is also more flexible than PVC. If you’re using long lengths of CPVC, you’ll need to add support every 3 feet.

When to Use PVC Pipes

When you’re deciding on the necessary materials you’ll need for your construction projects, consider the pros and cons of PVC pipes. There are many cases when PVC is the better and more affordable choice. The following are a few of the best instances when you can use PVC pipes:

Indoor Plumbing

Because PVC pipe is made to be resistant to virtually all corrosive chemicals and gases, it’s a great choice for transporting drinking water. It has insulation properties, as well, so the temperature of the water it carries won’t be affected by outside temperature.

Many people use PVC for drainage and cleanouts, but it can be used for plumbing in many cases. However, where there are temperature limitations, it will be better to use CPVC.

Cold-water Applications

One of the best applications for PVC is transporting cold water. This is because it is a great insulator, so it will keep water cold and clean. 

Limited Outdoor Applications

PVC is commonly used for drainage and other underground applications. It can last indefinitely when it is installed correctly. However, this doesn’t mean it’s weather-resistant. Exposed PVC outdoor will be vulnerable to direct sunlight and freezing temperatures.

Pressure Systems and Non-pressure Systems

A pressure system has to do with a change in sea-level distribution. You always need to check your local requirements to verify your PVC or CPVC is appropriate in your area. However, PVC is frequently the best choice for pressure systems and non-pressure systems. Common pressure-system applications for PVC include main water and service lines, drinking water lines, irrigation lines, and swimming pools and fountains. Non-pressure systems that can use PVC are sanitary drainage systems, sewer lines, and storm or roof drainage, among others.

When to Use CPVC Pipes

In many cases when PVC is used, CPVC can also be used. But because of the differences in the materials, there are some applications in which only CPVC can be used. Consider the following:

Hot-water Applications

Because CPVC can withstand water up to 200 F, it is a much better choice than PVC for hot-water applications. 

Water-supply Applications 

Clearly, because of the chemical makeup and the low cost of PVC and CPVC, these are the best choice of material for water transport in most cases. A few common uses for CPVC are transporting drinking water and drainage. 

Fire Sprinkler Systems 

You might think that CPVC would melt in a fire, but it has actually “achieved the best possible fire-protection classification” (per Blazemaster). It has low flammability, doesn’t smoke and doesn’t result in burning droplets. Therefore, CPVC is an ideal material for fire sprinkler systems.  

Not for Applications in Freezing Conditions 

PVC and CPVC have maximum and minimum water temperatures that they can withstand. Although both types of pipes can keep water cold, they cannot withstand freezing temperatures. Therefore, you cannot install CPVC piping in a location that will potentially be exposed to temperatures under 32 F.

Final Verdict: When to Use PVC vs. CPVC 

There are very few instances when PVC and CPVC can be used interchangeably. When you’re trying to decide when to use PVC or CPVC pipes, be sure to consider the abilities and limitations of both. PVC is best for cold-water applications and pressure and non-pressure systems while CPVC is better for hot-water applications, water supply and fire sprinklers. 

About the Author

Mark Ligon
Mark Ligon is the marketing manager at PVCFittingsOnline.com, a supplier of PVC pipe, fittings, valves, plumbing supply and more.

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