CPVC pipe ratings can look confusing — SDR, CTS, SCH 80. Here is what they mean in plain terms so you buy the right pipe.
SDR — wall thickness & pressure
SDR (Standard Dimension Ratio) is the pipe's outside diameter divided by its wall thickness. A lower SDR means a thicker wall and a higher pressure rating:
- SDR 11: thicker wall, higher pressure — the common choice for hot & cold plumbing.
- SDR 13.5: thinner wall, lower pressure — used for lighter cold-water lines.
CTS vs SCH 80
| System | Wall | Used for |
|---|---|---|
| CTS (Copper Tube Size) | Sized like copper tube, rated by SDR | Home & building plumbing |
| SCH 80 (Schedule 80) | Much thicker wall | Industrial / high-pressure |
Common CPVC sizes
| Size (inch) | Size (mm, approx) | Typical use |
|---|---|---|
| ½" | 15 mm | Branch lines to taps & geysers |
| ¾" | 20 mm | Main branch / riser feed |
| 1" | 25 mm | Risers & supply mains |
| 1¼"–2" | 32–50 mm | Larger building mains |
Which to buy
For normal home hot- and cold-water plumbing, CTS CPVC, SDR 11 is the standard. Always join with CPVC-grade solvent cement (not PVC cement).
See CPVC pipes & fittings, the correct solvent cement, and our pipe size chart.