Guides / Hot tubs, saunas and plunges · Updated
DIY cold plunge
From maker manuals and catalogs, checked November 1, 2026.
Short answer
Most DIY plunges are a stock tank, 100 to 150 gallons, with a small water chiller. A chest freezer works for some people, but makers say freezers are for food storage only, so you’re on your own warranty-wise. Whatever you build, put it on a GFCI-protected outlet.
Stock tank sizes
| Tank | Size | Holds |
|---|---|---|
| Rubbermaid FG424300 | 52 × 31 × 12 in | 50 gal (only 12 in deep) |
| Rubbermaid FG424288 | 53 × 31 × 25 in | 100 gal |
| Rubbermaid FG424500 | 58 × 39 × 25 in | 150 gal |
| Behlen 2 × 2 × 4 ft steel | 23.5 in tall | 103 gal |
| Behlen 2 × 2 × 6 ft steel | — | 169 gal |
| Behlen 4 × 2 ft round | 24 in tall | 165 gal |
Behlen: sizes are nominal and exact dimensions “may vary slightly by model.”
Chest freezers
Freezer makers don’t support it. Frigidaire’s chest freezer manual: “This appliance is for storage only and should not be used for any other purpose.” GE’s warranty excludes failures from use “for other than the intended purpose”, and its manual says not to use an extension cord or leave the freezer in rain or direct sun.
Chilling it
A chiller is sized by how much heat it pulls out an hour. The cold plunge chiller calculator shows how long a 5,000 or 10,000 BTU/hr unit takes to chill your tank and what it costs to hold the temperature.
Electrical
Water and power need a ground-fault circuit interrupter. CPSC recommends GFCIs on pumps and electrical equipment used with pools, spas and hot tubs, and on outdoor receptacles within 20 ft of the water. Codes don’t name cold plunges, so ask your inspector how they treat yours.