While doing a new home inspection for a customer in Gilbert I mentioned new PEX water supply lines have been installed in their home. When they saw a picture of the plastic water lines they immediately became concerned it was the older plastic water lines they heard about, polybutylene. I assured them that the new PEX water lines are nothing like the older polybutylene lines found in houses built in the 1980s and early 1990s (If you’re unfamiliar with polybutylene water lines, and the problem with them, you can read more information about it on my website: “what is polybutylene plumbing”).
PEX water pipe is also known as cross-linked polyethylene. It has been used in Europe since the 1970s, but has only become a popular replacement for copper plumbing in the United States over the last decade. My first experience with PEX water lines was back east in radiant floor heating. Now most homes I inspect build in the Gilbert and the Phoenix area since the mid 2000s have PEX hot and cold water lines installed.
Some of the benefits of PEX plumbing include:
- Expected life of PEX pipes can reach 50+ years, although most only carry a 25 year warranty.
- PEX piping is more resistant to freezing temperatures than copper or PVC pipes.
- PEX tubing does not transfer heat as readily as copper, and so conserves some energy.
- Copper pipes can corrode over time but PEX does not have this problem. PEX also does not develop “pinhole” leaks like copper pipes can over time.
- PEX water lines are easier to install. Generally fewer connections and fittings are needed in the installation.
- PEX is less expensive than copper, both the material and installation.
- The “water hammer” noise of copper piping is virtually limited with PEX.
The only downside to PEX piping is it deteriorates if exposed to sunlight. The integrity of the PEX tubing can be compromised if exposed to direct sun light for as little as 30 to 60 days. There were also some problems with some of the earlier brass fitting (known as “yellow brass”) due to a chemical reaction between the hard water and the zinc in the fittings, but this has been resolved by changing the materials used in the fittings. Generally home inspectors have not noticed any problems with PEX plumbing in the last 10 years.