Stock Tank Cold Plunge DIY: Best Tank Size, Chiller or Ice

Quick Answer

A stock tank cold plunge is the easiest DIY build available. Get a 100-150 gallon stock tank, connect a cold plunge chiller (or add a submersible pump if your chiller has none), then wrap and cover the tank. The build costs about $700 with a 1/3 HP chiller or $900-$1,150 with a 1 HP chiller; with ice instead of a chiller it is about $300-$350 (estimated parts cost). Total build time is 2-3 hours with no sealing, no electrical modifications, and no waterproofing required. The stock tank is already watertight out of the box.

This method is our top recommendation for beginners and anyone who wants a reliable cold plunge without the complexity of a chest freezer conversion.

Why Choose a Stock Tank

Stock tanks are built for one purpose: holding water for livestock. That means they are inherently watertight, corrosion-resistant, and designed to sit outdoors for years. Here is why they work so well as cold plunges:

• No waterproofing needed: Unlike a chest freezer, the tank holds water without any sealant or modification
• Built-in drain plug: Most stock tanks have a threaded drain at the bottom, making water changes simple
• Metal construction aids cooling: The galvanized steel transfers heat away from the water, which helps your chiller work more efficiently
• Durable for decades: These tanks are made for farm use in harsh conditions. A cold plunge is easy duty by comparison.
• Easy to move: At 30-50 lbs empty, you can reposition the tank anytime

The main trade-off compared to a chest freezer is that you need a separate chiller unit to cool the water. A stock tank has no built-in refrigeration, so your total cost is about $700-$1,150 depending on the chiller you choose (estimated parts cost). However, the build is dramatically simpler and you get more interior space than a chest freezer for less money.

How Much Does a Stock Tank Cold Plunge Cost?

These are rounded estimates of the whole build's parts cost. The chiller decides most of the cost.

Totals leave out tax and sanitizer. The AS ColdPlunge 1 HP we review was out of stock when we checked, so the 1 HP range uses comparable in-stock 1 HP chillers. A galvanized tank bought locally can cost less than the Brute. Prices move, so see today's price on each part before you buy. For chiller picks by use case, see our cold plunge chiller guide.

Stock Tank Comparison

The two main options are galvanized steel and structural poly (plastic). Both work, but galvanized tanks are more popular for cold plunges because they conduct heat better and look more premium.

Our pick: The 100-gallon galvanized oval from CountyLine (sold at Tractor Supply) is the most popular choice in the cold plunge community. The oval shape fits the human body better than round tanks, and 100 gallons provides enough depth for chest-level submersion while seated.

Oval vs. Round

• Oval tanks are better for taller users (5'10"+) who want to stretch their legs slightly. The 52" length gives you room.
• Round tanks are better for compact spaces and for users under 5'10". The 39" diameter is tight but workable in a seated position.
• 150-gallon round is the best option if you want maximum space and do not mind the larger footprint.

Galvanized vs. Plastic

• Galvanized steel conducts heat better, helping the chiller cool the water faster. It also looks better and lasts longer. The downside is potential rust over many years, though galvanized coating prevents this for a long time.
• Poly (plastic) is lighter, cheaper, and completely rust-proof. However, it insulates the water slightly (which means the chiller works harder) and can flex under load.

Chiller Comparison for Stock Tanks

Since a stock tank has no built-in cooling, you need an external water chiller. The chiller pulls water from the tank, cools it, and returns it. Here are our recommendations, based on manufacturer specs and owner reports:

Running cost is estimated monthly electricity: $ under $15, $$ $15–$30, $$$ over $30, depending on climate and insulation.

Our pick: For a 100-gallon stock tank, the 1/3 HP chiller is sufficient if you live in a mild climate (average temps below 85°F). If you are in a hot climate or want faster cool-down times, the 1 HP unit is worth the investment. The 1 HP System bundle includes an inline filter, which saves you from buying a separate filtration setup.

For detailed chiller comparisons across all brands, see our chiller reviews page.

Do You Need a Chiller?

If you are on a tight budget, you can skip the chiller and use ice instead. A 100-gallon stock tank requires approximately 40-60 lbs of ice to drop the water temperature from 70°F to 45°F. Buying that much bagged ice gets expensive fast if you plunge daily. A chiller pays for itself within 2-3 months of daily use compared to buying ice.

Submersible Pump and Plumbing

You need a pump to circulate water between the tank and the chiller. The pump sits inside the tank and pushes water through vinyl tubing to the chiller and back.

If your chiller already has a built-in pump (the AS ColdPlunge units do), skip this section.

Our pick: The Vivosun 800 GPH is the community favorite. It is powerful enough to push water through most chillers, and runs nearly silent. Pair it with 1/2" or 3/4" vinyl tubing and stainless steel hose clamps.

Step-by-Step Setup

Step 1: Position the Tank

Choose a flat, level surface that can support 850+ lbs (the weight of 100 gallons of water plus the tank). Good options include:

• Concrete patio or garage floor: Ideal. No preparation needed.
• Wooden deck: Check that the deck is rated for the weight. Distribute load with plywood underneath.
• Gravel pad: Level it first. Add a sheet of plywood on top for stability.
• Grass: Not recommended. The tank will sink, become unlevel, and the bottom will stay damp.

Place the tank near an outdoor electrical outlet for the chiller and pump. Keep all electrical equipment on a GFCI-protected circuit.

Step 2: Seal the Drain Plug

Stock tanks come with a built-in drain plug, which is convenient for water changes but can develop slow leaks at the threads.

• Apply a wrap of plumber's Teflon tape around the drain plug threads
• Hand-tighten the plug firmly
• Apply a small bead of marine sealant around the outside of the plug as insurance
• Test by filling with 4-5 inches of water and checking for drips over an hour

Step 3: Connect the Chiller Plumbing

This is the most involved step, but it is straightforward.

1. Place the submersible pump inside the tank
2. Run vinyl tubing from the pump's outlet to the chiller's "Water Inlet" port
3. Run a second length of tubing from the chiller's "Water Outlet" port back into the tank
4. Secure all connections with stainless steel hose clamps
5. Fill the tank with water from a garden hose

Tip: Route the return line so it enters the water below the surface to prevent splashing and reduce noise.

Step 4: Insulate the Tank (Optional but Recommended)

An uninsulated galvanized tank loses heat quickly in warm weather, forcing the chiller to run harder and costing more in electricity. Basic insulation reduces energy costs by 25-40%.

• Reflective bubble wrap: Wrap the exterior in reflective insulation such as Reflectix. Secure with foil tape.
• Rigid foam board: Cut 1" thick foam board to fit around the tank for even better insulation. Attach with construction adhesive or straps.
• Insulated cover: Use a fitted hot tub cover or a custom-cut foam board lid to prevent heat gain from the top. This is the single most impactful insulation upgrade.

For a detailed guide on insulation options and their cost-effectiveness, see our cold plunge insulation guide.

Step 5: Power On and Set Temperature

1. Plug the chiller and pump into a GFCI outlet
2. Set the chiller to your desired temperature (start at 55°F for beginners)
3. Let the system run for 4-8 hours to reach the target temperature
4. Test the water temperature with a thermometer before your first plunge

Expected cool-down times (from 70°F tap water):

• 1/3 HP chiller to 50°F: 6-8 hours
• 1 HP chiller to 50°F: 2-4 hours
• Ice method to 45°F: 15-20 minutes (but temporary)

Maintenance

Stock tank maintenance is simpler than a chest freezer because you have easy drain access and no interior seams to worry about.

Weekly

• Check and adjust sanitizer levels (hydrogen peroxide or non-chlorine shock)
• Wipe the waterline to prevent biofilm
• Clean the pump's intake screen

Monthly

• Rinse or replace the inline filter (if using one)
• Check all hose clamp connections for tightness
• Inspect the drain plug for slow leaks

Every 3-4 Months

• Full water change via the drain plug
• Scrub the interior with a soft brush and white vinegar
• Inspect the galvanized coating for any rust spots (sand lightly and apply cold galvanizing spray if needed)

For a comprehensive water care protocol, see our water care and maintenance guide.

Frequently Asked Questions

How long will a galvanized stock tank last as a cold plunge?

Galvanized steel tanks are rated for 15-20+ years of outdoor use holding water for livestock. As a cold plunge with treated water, expect at least 10 years before any significant rust develops. Keeping the water's pH between 7.2-7.6 protects the zinc coating.

Can I use a stock tank cold plunge without a chiller?

Yes, but you will need to add ice before each session. For a 100-gallon tank at 70°F, you need about 40-60 lbs of ice to reach 45°F. This works for occasional use but becomes expensive for daily plunging. A chiller is the better long-term investment.

Is 100 gallons enough for a tall person?

A 100-gallon oval tank works for most adults up to 6'2" in a seated position with knees bent. If you are taller or want more room, consider a 150-gallon round tank. For comparison, most commercial cold plunge tubs hold 80-120 gallons.

Do I need to worry about electrical safety with a stock tank?

Yes. Even though the tank itself is not powered, your chiller and pump are electrical devices near water. Always use a GFCI-protected outlet. Unplug the pump before getting in if it sits inside the tank. The chiller stays plugged in since it is outside the tank.

Will the stock tank rust?

Galvanized steel is zinc-coated to prevent rust. With properly balanced water chemistry and a pH between 7.2-7.6, the galvanized coating will last many years. If you notice any rust spots, sand them lightly and apply cold galvanizing spray from a hardware store.

How much does it cost to run a stock tank cold plunge per month?

Your main ongoing costs are electricity for the chiller ($15-$35/month depending on the unit and climate) and water treatment supplies ($5-$10/month). Total monthly cost is typically $20-$45, which is comparable to a gym membership.

Related Guides

• DIY Chest Freezer Cold Plunge -- A cheaper build with built-in cooling, but more complex setup
• DIY Cold Plunge Overview: All Build Methods -- Compare all 6 DIY approaches side by side
• Cold Plunge Water Care & Maintenance -- Keep your water clean and bacteria-free
• Getting Started with Cold Plunge -- Temperature protocols and beginner safety
• Cold Plunge Insulation Guide -- Reduce chiller energy costs
• Winterizing Your Cold Plunge -- Protect your outdoor setup in freezing weather

Sources

• NLM Review: Cold Water Immersion and Recovery
• CDC: Healthy Swimming and Water Safety
• Journal of Sports Sciences: Effects of Cold Water Immersion on Muscle Soreness