Water Heater Experts

How to Protect Your Water Heater in Winter

Simple steps to prevent freeze damage and keep hot water flowing when temperatures drop.

Published: August 30, 2026

Cold weather is hard on plumbing, and your water heater sits right in the middle of it. A tank or tankless unit in a garage, attic, basement, or crawlspace can be exposed to freezing temperatures, and the pipes feeding it are often the first to freeze. Winterizing your water heater takes an afternoon and can save you from a burst pipe or a cracked heat exchanger.

Here is a practical checklist to run through before the first hard freeze.

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Why Winter Is Hard on Water Heaters

Three things happen when the temperature drops. Incoming water is colder, so the heater works harder and takes longer to recover. Exposed pipes are more likely to freeze, and water expands as it freezes, which can split copper and plastic lines. And units located in unconditioned spaces — garages, attics, crawlspaces — face the most risk. Planning ahead addresses all three.

Insulate and Protect the Unit

Insulate the Tank and Pipes

An insulating blanket on an older tank reduces standby heat loss and helps the unit keep up with colder incoming water. Check the manufacturer's guidance first; newer units with foam insulation may not need a blanket and some warranties specify against covering certain parts.

Pipe insulation matters even more. Foam sleeves on the hot and cold lines running to and from the heater — especially the first several feet — protect against freezing and reduce heat loss. Pay attention to elbows, tees, and any section near a vent, foundation, or exterior wall.

Protect Units in Cold Spaces

  • Garage units: Keep the garage door closed as much as possible and consider a small space heater in severe cold if the unit is rated for the location.
  • Attic units: Insulate the unit's pipes and any exposed plumbing, and confirm the platform and drain pan are intact.
  • Crawlspace units: Insulate thoroughly and seal gaps that let cold air blow across the pipes.
  • Outdoor tankless units: Verify freeze-protection is enabled and that the installation is rated for outdoor use.

Tankless Freeze Protection

Many tankless water heaters include a freeze-protection feature that warms internal components when temperatures drop. That protection usually depends on the unit having power, so do not unplug it in winter, and check the manual for the exact temperature at which it activates. In extreme cold, keeping a trickle of water running through the unit can help, and some units allow a drain-down procedure if the home will be empty. Never let a tankless unit freeze with water trapped inside the heat exchanger.

Drain the Tank If the Home Will Be Empty

If you will be away or the home will sit unheated through freezing weather, draining the water heater prevents ice damage. Our step-by-step water heater draining guide covers the safe procedure. For a tankless unit, follow the manufacturer's winterization or drain-down instructions, which often include opening the purge valves and using compressed air to clear the heat exchanger.

Adjust Settings for the Season

Colder incoming water means longer recovery times, but raising the thermostat is not automatically the answer. Keep the setting within a safe range — see what temperature a water heater should be set to — and use a mixing valve or consider more capacity if your household consistently runs out. Our guide to running out of hot water covers the possible causes.

Check Venting and Combustion Air

On gas and propane units, confirm the flue is clear and that combustion air intakes are not blocked by snow, ice, or debris. A blocked vent is a carbon monoxide hazard. Make sure the outdoor termination of a high-efficiency unit stays clear after snowstorms, and never stack anything against the unit.

Watch for Warning Signs

  • Hot water that runs cold much faster than usual
  • Frost or condensation on the tank, pipes, or fittings
  • Unusual noises or error codes on a tankless unit
  • Any sign of water where it should not be

If you notice these, address them before the next cold snap. See our list of signs your water heater needs replacement if the unit is already old.

When to Call a Professional

Insulating pipes and adjusting settings are safe DIY tasks. Gas connections, venting repairs, freeze damage to a heat exchanger, and electrical work should be handled by a licensed technician. If your unit is in a vulnerable location or has already frozen once, have it inspected to confirm there is no hidden damage.

A little prevention in the fall keeps you from scrambling for emergency service in the middle of a cold spell. If you are unsure whether your setup is ready for winter, a professional inspection is a small cost compared with a burst pipe.

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