At What Temperature Will My Pool Pipes Freeze? (And How to Prevent It)

Swimming Pools Blog

Short answer: pool plumbing starts to freeze at 32°F (0°C), because that’s when water turns to ice. But the risk window depends on a few real-world factors—water movement, exposure, and how well your system is winterized.

Below is a clear, homeowner-friendly guide to what actually happens, what to watch for, and how to protect your equipment.

The Freeze Line: What Temperature Triggers Trouble?

  • 32°F (0°C) is the threshold. If standing water sits in pipes or equipment at or below freezing long enough, it will start to crystallize and expand.
  • How fast can it happen? If the air is below 32°F and water is sitting still in exposed equipment, ice can start forming in under an hour. Running water resists freezing longer, and underground lines take longer—often several days of continuous freezing—because the surrounding soil insulates them. (Read More)

Key takeaway: danger rises quickly for above-ground equipment (pumps, filters, heaters, skimmers) during a hard freeze; underground pipes are safer but not immune if the cold snap lasts.

Factors That Make Freezing More (or Less) Likely

  1. Water Movement
    Circulating water is slower to freeze. Many owners run the pump during overnight freezes to buy time.
  2. Exposure & Insulation
    Equipment pads, plumbing elbows, and vertical risers at the equipment are the first to freeze. Insulating exposed pipes and components reduces risk. (Read More)
  3. Duration of the Cold Snap
    A brief dip to 30°F may not freeze buried lines, but multi-day freezes can.
  4. System Prep (Winterization Quality)
    The most reliable way to prevent damage is removing water from lines and equipment (blowing out), opening drain plugs, and protecting the skimmer before the first freeze. (Read More)

What Freezes First (and Why It Matters)

  • Pump housings & lids – thin walls, exposed to wind.
  • Heater headers – metal/plastic manifolds that trap pockets of water.
  • Filter tanks & multiport valves – water often remains unless drained.
  • Skimmer throats & lines – shallow and near the surface.

These components can crack if ice expands inside them. Calm Water Pools notes that heater headers are especially susceptible during sudden freezes—always remove the drain plugs and clear water. (Read More)

Prevention Checklist (Use This Before the First Hard Freeze)

  • Open drain plugs on the pump, filter, and heater; let water out. If you’re winterizing for the season, blow out the lines to move trapped water back to the pool. (Read More)
  • Lower the water level just below the skimmer so skimmer water can’t freeze and expand. (Read More)
  • Insulate exposed plumbing and consider a frost guard or freeze protection controller to automatically run the pump near 32°F. (Read More)
  • Cover the pool for winter. A tight, well-fitted safety cover keeps out debris, reduces heat loss from wind over the water surface, and supports proper winter water levels—all of which help minimize freeze risks to the system. Learn more about Calm Water Pools’ Winter Safety Covers. (Read More)

“It’s Freezing Tonight—What Should I Do Right Now?”

If you haven’t fully winterized and a hard freeze is forecast:

  1. Run the pump continuously through the coldest hours to keep water moving.
  2. Open equipment drain plugs (pump, heater, filter) if you can’t ensure continuous circulation.
  3. Protect the skimmer (use a gizmo or lower water below skimmer) to avoid cracking. (Read More)
  4. Throw on your safety cover and secure it to reduce wind exposure and keep debris out—this also helps the pool hold a proper winter level that supports your cover and plumbing plan. Winter Safety Covers. (Read More)

Frequently Asked Questions

Does wind chill matter for pipes?
Wind doesn’t lower the actual air temperature, but it pulls heat away faster, so exposed equipment reaches 32°F sooner. Translation: windy freezes are riskier for pumps and heaters.

If my lines are buried, am I safe?
Safer, yes—but not if the freeze lasts for days. Soil slows but doesn’t stop heat loss. (Read More)

What’s the role of a safety cover in freeze protection?
A tight, custom-fit safety cover supports the correct winter water level, blocks debris (which can clog skimmers/lines), and helps stabilize conditions under the cover. Calm Water Pools offers Latham® solid and mesh safety covers—Winter Safety Covers. (Read More)

Bottom Line

  • 32°F (0°C) is the number—but time, exposure, and prep decide whether you get damage.
  • Above-ground equipment can start freezing in under an hour during a hard freeze; underground lines usually require sustained freezing to be at risk. (Read More)
  • The best defense: drain and/or blow out equipment and lines, insulate exposed plumbing, maintain the right winter water level, and use a proper safety cover. Start here: Winter Safety Covers. (Read More)