How To Winterize My Hot Tub | What Techs See in Spring

Every spring, spa repair techs see the same pattern: someone drained their hot tub, tossed on the cover, and now the pump housing is cracked or the plumbing has split. It’s an expensive way to learn that water expands when it freezes, and trapped water destroys equipment from the inside.

Winterizing your hot tub isn’t complicated, but it demands one early decision — whether you plan to keep it running all winter or completely shut it down until spring. Each path has its own steps, and mixing them up is how the damage happens. Here’s how to choose the right approach for your spa and your schedule.

The First Question That Saves Your Spa

Before touching the drain valve, decide on your winter plan. The two main approaches boil down to “keep it running” or “full shutdown.” If you live in a climate that drops below freezing and you won’t be using the tub for a month or more, a full winterization is the safer route.

Keep it running is the simpler choice if you plan to soak a couple of times a week. The spa stays filled, the heater stays on, and you maintain the water chemistry like normal. Manufacturers generally recommend this for short cold snaps or regular winter use.

Full shutdown is for seasonal closure. It means clearing every drop of water from the plumbing, pumps, and heater so that no freeze damage occurs. This takes a full afternoon but buys months of worry-free storage.

Why “Just Cover It” Fails in Freezing Weather

The most common winterization myth is that a solid cover protects the tub from freezing. The cover is critical, but it only helps if the water inside is moving or completely absent. Here’s what gets overlooked:

• Stagnant water in the plumbing: When water sits still in the pipes and temperatures drop, it freezes and expands, often cracking the PVC or flex lines. A cover doesn’t prevent this.
• Skipping the antifreeze step: After draining, a small amount of water clings to the inside of the pipes. RV antifreeze (propylene glycol) is non-toxic and prevents that residual water from freezing and causing damage.
• Ignoring the air blower: The air blower system traps water even after the main drain is open. Failing to drain it allows a freeze plug to form, which can crack the blower housing or the check valve.
• Forgetting pump drain plugs and heater unions: Pumps and heaters hold water in low spots. Removing the drain plugs and loosening the unions lets that trapped water escape. Without this step, the pump seal and heater core often fail.

These oversights regularly lead to $500 to $1,500 in spring repairs, which is more than the cost of a proper winterization kit.

Full Shutdown — The Step Most People Skip

A proper full winterization follows a logical order, and the sequence matters. Industry experts from Royalspa two winterizing approaches clearly, emphasizing that a full shutdown is a specific procedure, not just draining the water.

Start by turning off the power at the breaker — never skip this, because running a pump dry destroys the motor within seconds. Then drain the spa completely using the drain valve or a submersible pump.

After the main drain, open the air blower valve to release any water trapped in that system. Remove the pump drain plugs and loosen the heater unions. Finally, use a shop vacuum on the filter standpipe and the jet openings to pull out any sitting water.

Once the lines are clear, pour RV antifreeze directly into the filter standpipe and through the jets while using the vacuum to pull it through the lines. This coats the inside of the pipes and protects against any residual moisture.

Choosing between these two paths depends entirely on whether you’ll be using the tub during the coldest months. If you plan to soak regularly, winter maintenance is the simpler route.

Winter Maintenance — Keeping It Running Without Disaster

If you decide to keep your spa running through the winter, you can mostly use it as normal — with a few extra precautions. The cold creates unique conditions that require some adjustments to your routine. Here’s what to watch for:

1. Check chemical balance weekly: Cold air holds less moisture, which can increase water evaporation and concentrate the dissolved solids. Test pH and sanitizer levels more often to prevent scale or bacterial growth.
2. Maintain a minimum temperature: Set your thermostat to at least 80°F, even if you aren’t using it for a week. Letting the water drop too low forces the heater to work much harder and increases the risk of freezing in the plumbing.
3. Keep the cover sealed: A quality cover with a snug lock-down system is your best defense. Snow and ice that build up on top actually provide extra insulation, so leave moderate accumulations in place.
4. Fill with hot water: When topping off the tub, use hot water from your house. Cold tap water will drop the spa temperature significantly and force the heater to run longer, which uses more energy.

The main risk with a running tub is a power outage. If the power goes out and the temperature drops below freezing, you have a limited window before the water in the pipes starts to freeze.

The Two Materials That Matter — Antifreeze and Cover Care

RV antifreeze is the standard for hot tub winterization, but not all antifreeze is the same. Automotive antifreeze (ethylene glycol) is toxic and must never be used in a spa, as it can contaminate the shell and cause health risks for the next fill.

Lesliespool’s 10-step winterization guide recommends using only propylene glycol-based antifreeze, which is non-toxic and safe for your equipment. One gallon is typically enough for a standard 6-person spa, but check your owner’s manual for the exact amount.

Cover care is equally important during storage. Before placing the cover, clean it thoroughly and treat it with a UV protectant. A cracked or waterlogged cover loses its insulating value and can sag under the weight of snow and ice.

The Bottom Line

Winterizing your hot tub comes down to one decision — run it or drain it. If you drain it, the key is getting every drop of water out and protecting the lines with RV antifreeze. If you run it, keep the water moving and the heater on.

These steps work for most standard portable spas, but your specific model may have a different drain valve, pump configuration, or air blower setup. Checking your owner’s manual or calling a local spa dealer is the safest way to confirm the process for your equipment.