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Quick answer: Charlotte Pipe recommends glycerin antifreeze for its CPVC water systems and for PVC pressure and DWV pipe. Glycol antifreeze has limits:
- Propylene glycol: over 50% can damage PVC; over 25% can damage CPVC.
- Ethylene glycol: fine in PVC up to 100%, but over 50% can damage CPVC. It is toxic, so Charlotte says keep it out of drinking water and food processing systems.
- ABS DWV is stricter: only 60% glycerol, 22% magnesium chloride, or “Plastic Pipe Antifreeze.”
All rules here come from Charlotte Pipe’s Plastics Technical and Installation Manual (page 75), read October 9, 2026 from the rendered page. They apply to Charlotte’s pipe; check the maker of your pipe and your local code. This page has no buy buttons.
Glycerin: how strong to mix it
Charlotte says to dilute glycerin antifreeze to the strength your job needs. Its best freeze protection is -51.7°F (-46.5°C), reached at 66.7% glycerin by weight. Above that, the mix works less well.
| Glycerin by weight | Freeze point °F (°C) |
|---|---|
| 0% | 32.0 (0.0) |
| 10% | 29.1 (-1.6) |
| 20% | 23.4 (-4.8) |
| 30% | 14.9 (-9.5) |
| 40% | 4.3 (-15.4) |
| 50% | -9.4 (-23.0) |
| 60% | -30.5 (-34.7) |
| 66.7% | -51.7 (-46.5) |
| Over 66.7% | Not recommended |
The percentages are by weight, not by volume. Keep that in mind before you mix.
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Propylene and ethylene glycol
Charlotte says propylene glycol and ethylene glycol solutions are suitable for pressure testing CPVC and PVC pressure and DWV systems, within these limits:
| Antifreeze | PVC | CPVC | Charlotte’s freeze protection figures |
|---|---|---|---|
| Propylene glycol | Over 50% may damage it | Over 25% may damage it | 25%: about 15°F (-10°C); 50%: -30°F (-34°C) |
| Ethylene glycol | OK up to 100% | Over 50% may damage it | 25%: about 8°F (-13°C); 50%: about -33°F (-36°C) |
- Charlotte says 25% propylene glycol solutions are approved for use with potable water systems.
- Charlotte says ethylene glycol is toxic and must be avoided in potable water and food processing systems.
- Notice the gap: a 50% propylene glycol mix is within Charlotte’s PVC limit but over its CPVC limit. On a mixed PVC and CPVC system, the CPVC limit is the one that matters.
- For other chemicals, Charlotte points to the Chemical Resistance chart in the same manual.
ABS drain lines: only three options
For ABS and ABS Plus DWV foam core systems, Charlotte allows only:
- 60% glycerol, by weight, in water. Use undiluted.
- 22% magnesium chloride, by weight, in water. Use undiluted.
- “Plastic Pipe Antifreeze” (made for plastic pipe).
Charlotte says not to use any other type of antifreeze in ABS.
Quick picks by job
- CPVC water lines: glycerin is Charlotte’s recommendation. If you pressure test with propylene glycol, stay at 25% or less.
- PVC pressure or DWV: glycerin is recommended; propylene glycol up to 50% and ethylene glycol at any strength are within Charlotte’s PVC limits. Keep ethylene glycol out of drinking water lines.
- ABS DWV: only the three products listed above.
FAQ
Can I use propylene glycol antifreeze in PVC?
Charlotte says solutions over 50% propylene glycol may damage PVC. For CPVC the limit is 25%.
What is the best antifreeze for CPVC?
Charlotte recommends glycerin antifreeze for its FlowGuard Gold and Corzan CPVC water systems.
How cold can glycerin antifreeze protect to?
Charlotte lists -51.7°F (-46.5°C) at 66.7% glycerin by weight, its maximum. It does not recommend going stronger than 66.7%.
What antifreeze can go in ABS drain pipe?
Charlotte allows only 60% glycerol, 22% magnesium chloride, or “Plastic Pipe Antifreeze” in ABS DWV, and says not to use any other type.
Related guides
- Winterize your plumbing: cold-weather checklist
- How to thaw a frozen pipe
- Best heat tape for water pipes
- CPVC installation do’s and don’ts
Sources
- TM-PL (PDF) (charlottepipe.com), read 2026-10-09