How do I winterize a deck-mounted hot tub in Moncton NB?

If you are shutting the hot tub down for winter, you need to fully drain it, blow out every line with a shop vacuum or air compressor, add plumbing antifreeze to the jets and pump, and secure a quality cover — or, alternatively, keep the tub running at a reduced temperature to prevent any freeze damage.

Moncton's winter temperatures regularly drop to minus 15 to minus 25 degrees Celsius, and the freeze-thaw cycling in southeastern New Brunswick is among the most frequent in the province due to the moderating influence of the Petitcodiac River and proximity to the coast. Water left anywhere in a hot tub's plumbing system will freeze, expand, and crack pipes, pump housings, or the shell itself. This is not a gradual risk — a single hard freeze below minus 10 can destroy a pump or split a PVC fitting overnight if there is residual water in the line.

The full winterization process starts with draining the tub completely. Open the drain valve and let gravity do the initial work, then use a submersible pump or wet vacuum to remove the last few centimetres of water that the drain cannot reach. This standing water in the footwell is where many homeowners make the mistake of assuming the tub is empty when it is not.

Next, blow out the plumbing lines. A shop vacuum set to blow mode, connected to each jet fitting with an adapter, forces air through the internal plumbing and pushes trapped water out through other jets and the drain. Work through every jet individually — hot tubs have multiple plumbing loops, and air blown through one jet does not necessarily clear water from a jet on a different circuit. An air compressor set to low pressure, around 30 to 40 PSI, also works well for this step.

After blowing the lines, pour non-toxic plumbing antifreeze — the pink RV and marine type, not automotive antifreeze — into each jet opening, the filter housing, and the pump intake. Use roughly 2 to 4 litres total distributed across all openings. This protects against any residual moisture that the air blowing did not fully remove.

Remove and store the filter cartridges indoors. Clean them first with a filter cleaning solution, let them dry completely, and store them somewhere that does not freeze. Filters left in the housing through winter trap water and become a breeding ground for bacteria that you will have to deal with in spring.

Secure the cover tightly. A properly fitted, insulated hot tub cover with locking straps is essential even on a drained tub. It keeps snow, rain, and debris out of the shell and prevents animals from nesting inside. Wind in Moncton can be significant, particularly during nor'easters, so locking clips or tie-down straps are not optional.

The alternative to full winterization is simply keeping the hot tub running through winter at a reduced temperature, typically around 30 to 32 degrees Celsius instead of the usual 38 to 40. The circulating water and active heater prevent any freezing, and many Moncton homeowners prefer this approach because they enjoy using the tub year-round. The operating cost is real — expect $80 to $150 per month in electricity depending on your tub's insulation quality and how often you use it — but it eliminates the winterization and spring recommissioning process entirely, and it avoids the risk of incomplete draining that leads to freeze damage.

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