Copper Versus PVC and CPVC Pipe

Copper pipe was used for years before pvc pipe for hot water was developed. PVC pipe suffered problems in hot water systems where the water was near the boiling point. This led to the invention of cpvc pipe for hot water. Yet you can find all three types of pipes in hot water systems. Let’s look at the pros and cons of each and the various ways they overlap.


Inertia drives far more in the modern world than we give it credit for, and this includes pipe sizes. Most PVC pipe is identified by its “schedule”. The PVC schedule gets larger as the pipe wall gets thicker. The inside bore of the pipe gets smaller. Schedule 40 is the most common type of 1 inch cpvc pipe. This has an outside diameter of 1.315 inches and a nominal pipe size of one inch. Schedule 40 pipe with an outer diameter of almost an inch has the nominal pipe size of three quarters of an inch. Yet you can find PVC pipe in CTS or copper tube sizes. CTS pipe sizes are larger than the schedule 40 pipe. CTS pipes will be labeled CTS, while other PVC pipes will be identified by their “schedule”. This means that you cannot use CTS pipe fittings on Schedule 40 PVC pipes though they’re both PVC. Copper pipe sizes are of course CTS.

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Material Incompatibilities

CPVC stands for chlorinated polyvinyl chloride. It is essentially a form of PVC with extra chlorine added to it to strengthen it and improve its ability to withstand high temperatures. Both types of plastic pipe can be recycled. They may be used in the same home. However, the performance of PVC pipe deteriorates at the temperature of hot water coming out of a maxed out hot water heater. This is why CPVC was invented. Some homes get by with copper pipe for the hot water delivery system but use PVC pipe for the rest of the home. Others use CPVC for the hot water delivery system, while the rest of the home has PVC pipe. CPVC pipe is a direct replacement for copper pipe if you have to replace the metal pipe, too, hence the labeling of CPVC pipe as having copper tubing sizes. Yet you cannot simply connected these various materials together.
PVC and CPVC are both plastics, but you need special adapters to connect them because they use different solvents to create leak-proof seals. Metal and PVC or CPVC pipe connections require even more exotic adapters, because metal and PVC pipe can’t be connected together unless you want it to leak there.


We’ve already addressed CPVC’s greater heat tolerance, explaining why it is replacing PVC pipe for hot water systems. The fact that it is easier to assemble and generally cheaper explains why it is replacing copper pipes. Yet copper pipes are still used. Copper pipes are anti-microbial and don’t bring a risk of plasticizers leaching into the water, though this fear is overblown. The fear of plasticizers also ignores the fact that copper itself can leach into the water, and the problem is made worse when the water is acidic. The longer the water sits in the pipes, the worse the build-up as well. Too much copper in your diet will cause stomach problems. One common solution is letting the tap run for 30 to 60 seconds before you drink from it, but now you’re wasting water.