When frigid winter weather strikes, which pipe material is most likely to survive freezing without rupturing? Every year, about a quarter million homes in the United States will be affected by water pipes that rupture due to freezing. The resulting damages — averaging more than $10,000 per incident — rank among the most common and costly homeowner insurance claims.

When Frozen Pipes Break

Freezing temperatures aren’t the only factor when a frozen pipe ruptures. In most cases, pipes don’t really freeze instantly at 32 degrees. Instead, latent heat that’s present in the water generally means temperatures need to drop into the low 20s before freezing occurs. About six hours of exposure to a hard freeze are normally required to potentially trigger a rupture.

Why Frozen Pipes Break

As ice forming inside a pipe expands laterally, it dramatically increases water pressure in the segment of pipe that’s not yet frozen. Eventually, this extreme water pressure exceeds the strength of the pipe material and rupture occurs.

Which Pipe Material Is Least Likely to Rupture?

  • Copper is a common residential water pipe that is resistant to deterioration. However, copper pipes are thin-walled and tend to lose heat rapidly, thus reaching the freezing point more quickly. Copper is also rigid and tends to split under pressure instead of expanding.
  • CPVC pipe (chlorinated polyvinyl chloride) is thicker than copper and thus retains heat slightly better. Unfortunately, CPVC is somewhat less rigid than copper, so it doesn’t expand sufficiently to accommodate excessive pressure due to ice formation. Since it’s a plastic material, it becomes brittle at very low temperatures and may fracture.
  • PEX pipe (cross-linked polyethylene) is known for flexibility that makes installation easier and configurable to many settings. That flexibility also makes PEX the pipe most likely to resist rupture in cold weather. However, PEX should not be considered totally immune to freezing. Adding pipe insulation and routing the pipe to avoid frigid air are also recommended to prevent rupture and resulting water damage.

For more information about the pros and cons of pipe material in your home, contact the plumbing pros at Mowery Heating, Cooling and Plumbing.