PVC and CPVC piping are some of the most durable and resilient types of piping in the world. These materials were engineered in the hopes of replacing traditional cast iron, copper, and iron pipes, which are expensive and prone to breakdown.
One of the many reasons that so many plumbers have turned to PVC and CPVC piping is because of the prevalence of chlorine in today's water systems. Chlorine is used in the public water system in cities across the country as a cleaner to remove harmful bacteria and contaminants from drinking water. Unfortunately, chlorine is a powerful chemical that can eat away at pipes from the inside out.
However, because of how PVC and CPVC are designed and its chemical composition, it is resilient against the damaging effects of chlorine - at least in the short term. If you're curious about the long-term effects that chlorine has on PVC and CPVC piping systems and whether or not you should expect problems in the future, you've come to the right place.
How Well Do PVC and CPVC Resist Chlorine?
Because of the chemical composition of PVC and CPVC piping, they are highly resistant to chlorine, and here's why.
PVC
Polyvinyl chloride, better known as PVC, is a plastic piping material that consists of a combination of ethylene and chlorine. Because chlorine is included in the design of PVC, it has a built-in resistance to its corrosive properties. As such, PVC piping holds up very well against chlorine and doesn't require the addition of additives or antioxidants for external protection.
CPVC
As with PVC, CPVC is highly resistant to chlorine and other chemicals. In many ways, CPVC, chlorinated polyvinyl chloride, is even more resistant to chlorine than PVC because of the additional chlorination process that goes into designing it. As such, it's the most resistant plastic piping when it comes to holding up against chlorine and doesn't require additional antioxidants or coatings for protection.
Long-Term Effects of Chlorine on Plastic Pipes
While PVC and CPVC are designed to hold up against chlorine in the short term, that doesn't necessarily mean they will hold up in the long term. To find out, let's look at how these materials stack up against other plastic pipes in terms of their long-term chlorine resistance.
PEX
PEX, which stands for cross-linked polyethylene, is one of the most common types of pipe used in residential and commercial plumbing systems today. PEX is very durable, affordable, and resistant to most chemicals, thanks to a special coating of antioxidants.
However, while PEX can hold up against chlorine in the short term, it struggles against it in the long term. Eventually, there's a good chance that chlorine will eat through PEX's protective coating and corrode the pipe from the inside out, resulting in leaks.
Polybutylene
Polybutylene pipes are commonly used in residential plumbing systems for hot and cold water lines. As with PEX, polybutylene is a polyolefin material, which means it only possesses hydrogen atoms that don't hold up well against chlorine. As such, it is coated with antioxidants to neutralize chlorine, but these antioxidants eventually wear away, leaving your polybutylene exposed to chlorine.
Polypropylene
As with polybutylene and PEX, polypropylene is a polyolefin material without natural immunity against chlorine. Polypropylene is often used in outdoor applications with irrigation and sprinkler systems. To aid against chlorination, it is coated with antioxidants that are helpful for a time but eventually wear away, along with the pipe itself.
PPR
Another plastic piping material commonly used for outdoor applications, polypropylene random copolymer plastic (PPR), doesn't hold up well at all against chlorine. PPR is a thicker plastic pipe, similar to PVC and CPVC. However, chlorine will eat away at the walls of the pipe and break it down from the inside out.
PVC and CPVC
In addition to holding up well in the short term, PVC and CPVC have the best long-term resistance to chlorine. Chlorine is rarely if ever, the cause for failure or breakdown with these types of pipes, and other causes are likely to cause issues before chlorine does. As such, PVC and CPVC are the preferred materials when chlorine is present.
Chlorine Exposure Ratings For Various Plastic Pipes
Because of the inherent danger that chlorine presents to plastic pipes, a special test was devised to determine how well different types of plastic hold up against chlorination. This test, known as the ASTM F2023, is the standard testing method for determining how oxidative stress from chlorine and other chemicals affects plastic.
As expected, PVC and CPVC are the only plastic pipes that hold up in the long term against chlorine. PEX, PPR, and other types of pipe that contain polyolefins are intended to last upwards of 50 years. However, when exposed to chlorinated water, their lifespan can end up being less than ten years.
How to Make Plastic Pipes Last Longer
Because chlorine is commonly used in city water supplies, plastic pipes such as PEX, polybutylene, and polypropylene have special coatings inside of them. These coatings protect against chlorination, but only to a certain extent. Once that coating wears off, there's nothing you can do to protect your plastic pipes.
As such, if you have experienced previous chlorine damage to plastic pipes, it's best to upgrade to PVC or CPVC piping systems. While these are also a type of plastic pipe, they contain chlorine atoms and have a natural immunity against chlorine that never goes away.
Signs You Should Replace Your Plastic Pipes
While chlorine is rarely the reason for PVC and CPVC pipes to break down, there are other things that can cause issues. Therefore, it's important to watch out for signs of breakdown so that you can take corrective measures.
- Cracks on the bottom or outside of the pipe.
- The water coming out of your pipes appears discolored, which indicates internal corrosion.
- You have less water pressure than normal, which could indicate internal breakdown resulting in a clog.
- Your pipe has a slight leak.
If you notice these issues, it's time to upgrade your plumbing system with new and chlorine-immune PVC or CPVC pipes.