The best cold plunge chillers for a bathtub

The submersible pump is what makes this the bathtub answer. A chiller normally needs a tub with inlet and outlet ports; a bathtub has neither. Dropping a pump into the water and running two hoses over the rim is inelegant and it works, and it is the cheapest route to a cold plunge for anyone who cannot give up floor space for a tub at all.

Six hundred watts is eleven cents an hour at full draw, comfortably mid-range here. The 79-gallon rating is a good match for a standard bathtub, which holds somewhere between 40 and 80 gallons at plunge depth.

The reusable metal mesh filter rather than disposable cartridges is a genuine running-cost detail that gets ignored because it is not electricity. Cartridge filters are a recurring purchase; a rinsable metal screen is not, and over a year that difference is larger than the difference in power draw between two chillers.

An availability note, because we said we would keep it current: this listing went to "Currently unavailable" on 2026-09-09 and we routed its buy link to a search rather than to a product nobody could add to a cart. Re-checked on 2026-09-12, it is back in stock with a buy-box offer, so the link points at the listing again.

Four of eight checklist items, and the two missing ones are the two that cost the most: there is no rated wattage and no gallon rating on this listing. Both computed cost components therefore score zero, and the total reflects that rather than working around it.

The unit this replaced published 600 W and a 79-gallon rating. We have not carried either figure across. A 1/3 HP compressor is not an unknown quantity - the two other 1/3 HP chillers here that do publish a draw sit at 280 W and 600 W - but attributing one manufacturer's number to another manufacturer's product is how a spec sheet becomes fiction, so the cells stay empty.

What it adds over the unit it replaced is control rather than cooling: 2.4 GHz WiFi with app scheduling and a top-mounted HD touchscreen, so the setpoint and the run schedule are reachable without crouching behind the unit. The filtration argument is unchanged and still a good one - a built-in pump and a reusable metal mesh element you rinse and refit, with no cartridges to buy.

The capacity line gives you two numbers rather than one, which is still rare here: a 79-gallon ceiling and a recommended working volume of about 53 gallons. Most listings in this category publish only the ceiling, which is the figure that flatters the unit. Treat the 53 as the real one - it is the volume the manufacturer itself points you at for the 41 F figure to mean anything.

The filtration is built into the case on this one: an integrated metal filter and an internal pump, so there is no cartridge to buy and nothing to re-plumb when you rinse it. The bathtub answer is the separate submersible pump and insulated hoses in the box - you drop the pump in the water and run the hoses over the rim, which is what makes a tub with no inlet or outlet workable without drilling anything.

No wattage is published, which costs it heavily here - both computed cost components score zero and no honest running cost can be given. Four of eight checklist items. The 1/3 HP units around it that do publish a draw sit between 280 and 600 W, but attributing one manufacturer's figure to another manufacturer's product is how a spec sheet becomes fiction, so the cell stays empty.

Direct-in-water cooling removes the entire plumbing problem: no ports, no hoses, no pump priming, no leak points. For a renter, that also removes the part of a cold plunge setup most likely to put water on a floor you do not own.

It costs you in power. At 1,200 W this is twenty-two cents an hour at full draw and, in the theoretical case of running continuously for a month, about a hundred and sixty dollars. It will not run continuously - it cycles to hold a setpoint like any refrigeration - but among the chillers here it is at the expensive end and the 280 W Pod Company unit is at the other.

The 150-gallon rating and the 39 F floor are both genuine capability. If you have a large tub and you want it properly cold rather than merely cool, this is a reasonable pairing, and the WiFi scheduling means you can have it chill overnight on a cheaper tariff if your utility has one.