DIY Cold Plunge: Stock Tank, Freezer or Chiller?

There are three common builds. A stock tank (the metal or plastic water trough sold at farm stores) filled with ice. A chest freezer filled with water that the freezer keeps cold. And either of those with a stand-alone chiller doing the cooling. Here is what each costs and where each goes wrong.

Stock tank and ice

This is the cheapest way to start, and the same deal as an insulated tub without a chiller, minus the insulation. You fill it from a hose and add ice. When the water gets dirty, you drain it. The weak spot is heat. Cooling 94 gallons by 15 degrees takes roughly 75 pounds of ice, and a bare metal tank in the sun warms back up quickly. The chiller vs ice guide has the full math.

A lid helps more than anything else you can add. So does keeping the tank in the shade or in a garage.

Chest freezer conversion

A chest freezer already has a compressor and an insulated box, which is why people turn them into plunges. You seal the inside seams, fill it with water and let the freezer cool it, usually on a timer so it doesn't freeze solid.

The trade-offs are real:

• Safety. You are sitting in water inside a mains appliance. Use a GFCI outlet and unplug it before you get in.
• Ice. A freezer is built to freeze, so the surface ices over if the timer is off. Plan to check it.
• Water. There is no filter or pump, so the water needs changing or treating more often than in a tub with a chiller.
• Warranty. The freezer's manual does not cover holding water. If the compressor dies, that is on you.

Adding a chiller

A stand-alone chiller works with almost any tub: it pumps water out of the tub and returns it cold and filtered. That turns a stock tank into a chilled plunge. But the chiller is most of the money.

Unbranded chillers sold for aquariums and DIY plunges cost less. I don't have spec sheets for them here, so check three numbers on any listing: horsepower, the coldest rated temperature, and the circuit it needs. Every chiller above asks for a dedicated circuit.

DIY vs buying a tub

Add a $3,599 chiller to a tank and you are within a few hundred dollars of Sun Home's horizontal tub with a 1 HP chiller built in, at $4,099. The ready-made tub is insulated, has a filter and ozone, and has one warranty for the whole thing.

An unfiltered tub needs fresh water every few days; see cold plunge water treatment. Outdoors, freezing is the risk: see cold plunge in winter.

Common questions

Is a chest freezer cold plunge safe?

It puts water next to an appliance that plugs into the wall, and a freezer is not made to hold water. If you build one, plug it into a GFCI outlet, keep the cord and plug dry, and unplug it before you get in. The freezer's manual will not cover this use, so expect no warranty help if it fails.

How much ice does a stock tank plunge need?

Cooling 94 gallons from 60°F to 45°F takes roughly 75 pounds of ice, before the water starts warming back up. A bare stock tank has no insulation, so the ice melts faster than in an insulated tub like the Ice Barrel 500 (R-16 foam).

Can I add a chiller to a stock tank?

Yes. Stand-alone chillers run water from the tub through a cooling unit and back, so they work with any tub that can take the two hoses. On the makers' stores in October 2026 they cost $3,599 (Sun Home, 1 HP), $3,990 (Plunge Pro) and $3,999.99 (Ice Barrel, 1/2 HP). Each needs its own circuit.

How heavy is a filled cold plunge?

Water weighs about 8.3 pounds a gallon, so a 100-gallon tub holds about 830 pounds of water before you get in. Ice Barrel lists 886 pounds for its 94-gallon Ice Barrel 500 full. On a deck or an upper floor, check what the floor can carry.