Two paths to a DIY cold plunge
The two most popular DIY cold plunge vessels are the Rubbermaid stock tank and a converted chest freezer. Both produce working plunges. They differ in cost, position, water volume, and DIY complexity. Here's how to choose.
Side-by-side
| Feature | Stock Tank | Chest Freezer |
|---|---|---|
| Vessel cost | $130 (new) | $50–$200 (used on Marketplace) |
| Water volume | 50 gal (typical) | 30–80 gal (depends on freezer size) |
| Position | Seated upright | Lying down (horizontal) |
| Insulation | None (requires aftermarket) | Excellent (built-in) |
| Cooling method | External chiller required | Freezer's own compressor (with controller) |
| DIY complexity | Easy (1 weekend) | Medium (2 weekends — liner, plumbing, controller wiring) |
| Portability | Medium (moveable empty) | Low (heavy, awkward to move) |
| Aesthetic | Rustic/agricultural | Appliance-like (can be hidden) |
| Lifespan | 10+ years (UV-stable plastic) | 5–10 years (compressor lifespan) |
Stock tank: the mainstream choice
The Rubbermaid 50-gallon Structural Foam Stock Tank is the most popular DIY plunge vessel for good reason. It's food-safe, structurally rated for livestock, fits through standard doorways, and has the largest ecosystem of compatible accessories (insulated covers, bulkhead fittings, ozone ports). Build cost with chiller: $500–$800.
The trade-off: stock tanks have no built-in insulation, so you'll need to add foam board around the sides and an insulated cover on top. They also sit upright, which means a seated plunge position — fine for most adults, but some users prefer the lying-down position of a freezer.
Chest freezer: the value choice
A converted chest freezer is the highest-value DIY plunge. You pick up a used 5–7 cubic foot freezer on Facebook Marketplace for $50–$150, line it with a food-grade PVC pond liner (to protect against any rust or chemical leaching from the freezer interior), fill with water, and use the freezer's own compressor — controlled by an Inkbird ITC-308 temperature controller — to maintain temperature.
Total build cost: typically $400–$600. That's $200–$300 cheaper than a stock tank build, and you get better insulation (chest freezers are designed to hold cold) and more water volume per dollar.
The trade-offs: chest freezers are horizontal, so you lie down in them rather than sit upright. Some people love this (it's relaxing); others find it claustrophobic. The lid springs need to be modified or removed (finger crush hazard). And the freezer's compressor is sized for freezing food, not cooling water — it works, but it runs more often than a purpose-built water chiller.
Which to choose: a decision framework
Choose the stock tank if:
- You want to sit upright during your plunge
- You want the largest ecosystem of compatible accessories
- You want to upgrade components later without rebuilding
- You have space for a visible plunge (stock tanks aren't easily hidden)
- You're willing to add your own insulation
Choose the chest freezer if:
- You want maximum value per dollar spent
- You prefer a lying-down plunge position
- You want excellent built-in insulation
- You can find a cheap used freezer locally
- You're comfortable with basic wiring (Inkbird controller)
The hybrid: stock tank + chest freezer chiller
Some DIYers combine the best of both: a stock tank for the vessel (upright position, accessory ecosystem) plus a chest freezer in another room, plumbed to act as a chiller. The freezer's compressor cools a glycol loop that runs through a heat exchanger in the plunge. This is more complex but delivers commercial-grade cooling at half the cost of a purpose-built chiller.
This is an advanced build — see our chest freezer build guide for the full instructions.
Whichever vessel you choose, our master DIY build guide walks through the full assembly. We also have dedicated guides for stock tank builds and chest freezer conversions.