PVC vs. CPVC Incompatibility

All FORMUFIT products are designed to fit standard and readily available Schedule 40 PVC pipe, including the plumbing-grade PVC pipe available at your local hardware store.

However, many hardware stores and home centers also carry a different type of pipe called CPVC, or Copper Tube Size (CTS) plastic pipe, which is not compatible with FORMUFIT and other brands of PVC fittings. Although CPVC pipes use a similar naming scheme (1/2", 3/4", and 1"), this can sometimes mislead customers away from standard pipe types. We've provided a quick guide below on what to do if your fittings don't fit and how to check if you may have picked up the wrong type of pipe.

I ordered (1/2", 3/4" or 1") fittings to match the markings on my pipe, but they are too big?

You may be trying to use CPVC pipe. Here's how to tell:

  1. Check the color first. CPVC is typically gold, yellow, or tan; Schedule 40 PVC plumbing pipe is a dull white.
  2. Check for markings. CPVC pipes will carry one of the following acronyms or names, as shown in the image:
  • CPVC
  • CTS
  • Copper Tube Size

If none of these markings are present on your PVC pipe or tube, you may have ordered the incorrect size for your Schedule 40 PVC pipe. In that case, please see our PVC 101 page on finding the right pipe size.

Go to PVC 101 Info Page

What's different about CPVC vs. PVC and why can't I use it?

CPVC was designed as a replacement for copper plumbing tubing, providing a water-potable and cost-effective rigid plastic solution. It is intended to fit into the same holes and locations as the copper pipes it replaces, resulting in a smaller outside diameter (OD) compared to typical white, Schedule 40 plumbing-grade PVC.

Due to these differences in measurement systems and the smaller size of CPVC and CTS pipe, they are not compatible with FORMUFIT fittings and accessories.

Is CPVC the same as PEX?

No, CPVC and PEX are not the same. While both are used for plumbing and potable water and replace standard copper in this role, they have distinct differences. PEX is a different type of material and does not connect to fittings with compression or solvents. Instead, PEX uses crimp, clamp, or push-fit fittings.

Like CPVC, PEX is also not compatible with FORMUFIT PVC fittings and accessories.

Is there anything I can do if my CPVC pipe wont work?

Yes. You can switch from CPVC to Schedule 40 PVC pipe of the equivalent size. If you haven't cut your pipe yet, most home centers and hardware stores will let you exchange your CPVC pipe for the Schedule 40 equivalent size. Bring your FORMUFIT fittings or note their sizes so you can confirm you're picking up true Schedule 40 pipe and not another CPVC size by mistake.

This is usually a more cost-effective solution than returning your items to FORMUFIT, as we do not carry CPVC-compatible products.