How to winterize a hot tub
Quick answer
If you are closing the tub somewhere it can freeze, the goal is to get every drop out of the plumbing, pump, and heater, since trapped water expands when it freezes and cracks pipes. Drain it fully, blow out the lines, sponge the footwell, leave it open to dry, and cover it. Many owners skip all this and simply keep the tub running through winter, which a well-covered tub does cheaply.
Winterizing is the one hot tub job where a missed step is expensive: water left in a pipe can split it. If you are not confident you can clear the plumbing completely, running the tub all winter is the safer choice.
If you are closing it down
- Power off at the breaker.
- Drain the tub fully through the spigot and a submersible pump.
- Clear the plumbing. Open the equipment drains, and blow the lines out with a wet-dry vac so no water sits in the pump, heater, or jets. This is the step that prevents cracks.
- Sponge out the footwell and any standing water, including under the filter housing.
- Leave it open to dry for a day, then cover it to keep weather and debris out.
Or keep it running
A hot tub is built for cold weather, and the heater plus circulation easily keep it from freezing. With a good cover the running cost in winter is modest, and you get to use it on the cold nights that are the whole point. The run-cost calculator shows what a cold-weather month looks like for your tub. If you travel, leave it running rather than half-drained, since a partly full tub is the worst case for a freeze.
Common questions
Can I leave water in it if I just keep the cover on?
Not safely in freezing weather without power. If the heater and pump are off, standing water in the pipes will freeze and can crack the plumbing. Either keep it running and heated, or drain it completely.
What is the most common winterizing mistake?
Leaving water trapped in the pump, heater, or a low jet line. The tub looks empty but a cupful in the wrong place freezes and splits a fitting. Blowing out the lines is what prevents it.
Is it cheaper to shut down or keep running?
For a single short trip, keep it running. For a whole winter unused, draining saves the running cost, but only if you clear the plumbing properly; a cracked pipe costs far more than a season of heating.