How to Winterize a Hot Tub in the Inland Northwest

The Inland Northwest doesn't mess around in winter. Liberty Lake, Newman Lake, and the surrounding communities along the eastern Spokane County corridor regularly see overnight lows drop to 0°F to –15°F during January cold snaps. Unlike the wetter, milder west side of the Cascades, our region gets dry continental cold — the kind that drives deep into unheated outbuildings and vacation cabins within hours of the furnace going out or the power failing.

A hot tub that is drained incorrectly — or not drained at all — will freeze from the outside in. Water expands roughly 9% when it freezes. Trapped inside PVC manifolds, jet bodies, pump volutes, and heater unions, that expansion has nowhere to go except through the material.

If your cabin near Newman Lake sits empty from October through April, or if you simply don't use your backyard spa through the colder months, a proper winterize is the single best investment you can make in the longevity of your equipment.

Step 1 — Run a Line Flush (Day Before)

Add a spa line flush product to the water the evening before you drain. Run the jets on high for 30 minutes. This purges biofilm — the slimy layer inside your plumbing — so it doesn't dry and calcify over winter. Drain and discard that water the next morning.

Step 2 — Cut the Power Completely

Go to your breaker panel and flip the GFCI breaker for the spa to the OFF position. Do not rely solely on the spa's topside control panel. Use a non-contact voltage tester at the equipment compartment to verify no live current before you touch any wiring or plumbing.

Step 3 — Drain the Tub

1. Locate the drain spigot (usually behind a small access panel near the base). Attach a garden hose and route it to a suitable drain area — not onto a slope above a road or neighbor's property.
2. Open the gate valve and let gravity do the work. A 400-gallon tub takes 45–90 minutes to gravity drain.
3. For faster draining at a vacation property, drop a 1/6 HP submersible pump into the footwell — you'll cut drain time to under 20 minutes.
4. Once most water is out, use your shop vac or a sponge and turkey baster to remove every last tablespoon from the footwell. Any standing water left here will freeze and crack the shell floor or drain fitting.

Step 4 — Remove and Clean the Filter(s)

Pull filter cartridges out. Rinse thoroughly, then soak in a filter cleaning solution, rinse again, and allow to dry completely before storage indoors. Do not store wet filters in the equipment bay — trapped moisture causes mold and the housing can crack if it freezes around a damp filter.

Step 5 — Blow Out All the Lines

This is the most important step and the one most homeowners do wrong.

1. Set your shop vac to blow mode (exhaust port).
2. Working around the tub systematically, press the vac hose firmly against each jet opening and blow for a full 15–20 seconds. You will see and hear water shoot out the drain. Do every jet, every return, every intake.
3. Open the equipment compartment. Locate the pump unions — typically two per pump (suction side and pressure side). Loosen and open these unions briefly to allow water to drain from the pump volute and plumbing connections. Retighten finger-tight only; you'll want them accessible in spring.
4. If your tub has a blower (air injector system), blow that line out separately — blower channels are a common freeze point that homeowners miss.
5. Blow through the heater manifold ports if accessible. Residual water in the heater tube is one of the most expensive freeze failures we see.

Step 6 — Add Non-Toxic Antifreeze to Residual Lines

Even after blowing, small pockets of water can remain in low spots and elbows. Pour approximately ½ cup of propylene glycol antifreeze into each jet opening after blowing it out. This is insurance, not a substitute for blowing the lines. Also pour a small amount into the pump unions before you retighten them.

Step 7 — Treat the Equipment Compartment

Wipe down the interior of the equipment bay with a dry cloth. Leave the equipment bay door slightly ajar if your tub's design allows it — trapped condensation in a sealed compartment accelerates corrosion. Do not use a heat lamp or plug in any device inside the bay over winter.

Step 8 — Secure the Cover

Replace the spa cover and lock it with the cover straps. At lake-area vacation properties, add hasp locks or cover clips to deter wildlife and wind damage. Heavy snow accumulation (Spokane can get 12"+ events) can permanently warp a cover — a cover cap rated for snow load is worth the $30–$50 investment.

There's no shame in hiring out a winterize. Here's when it genuinely makes sense:

• Vacation property more than 30 minutes away — if something goes wrong mid-process and you can't return easily, one mistake costs far more than the service call.
• Older or unfamiliar equipment — tubs made before 2010, or brands like older Dimension One, Marquis, or Sundance models, often have non-obvious low-point drains and secondary manifolds that require experience to locate.
• Hot tub was recently purchased used — you may not have an owner's manual, and the previous owner's "winterization method" may not have been correct.
• You noticed any leaks or soft spots in the equipment bay this season — winterizing over a slow leak means you'll open it in spring to a much bigger problem. Better to have a tech assess it first.
• Physical limitations — getting into the equipment compartment, crawling around jet openings, and operating a shop vac in awkward positions is genuinely hard work.

Liberty Lake Spa Repair has been servicing hot tubs throughout eastern Spokane County and the Idaho panhandle border for years. Our winterization service includes a full equipment inspection, line blow-out, antifreeze treatment, cover check, and a written condition report so there are no surprises in spring.

Whether you're a year-round Spokane Valley homeowner or managing a vacation property on one of our local lakes, we'll make sure your investment is protected all winter long.