Stock Tank Pool Hot Tub
If you’ve been around here for a while, you know we love our stock tank pool build. It’s been one of our favorite backyard upgrades, especially in the summer.
But for years, I kept getting the same question:
“Can you turn it into a hot tub?”
So… I finally did it.
And honestly, it’s a lot simpler than you might think. This is a simple DIY stock tank hot tub setup using a propane heater that turns your stock tank pool into a usable hot tub year-round.
How It Works
This setup builds off a standard stock tank pool system:
Water is pulled from the tank →
Runs through the pump →
Goes into the filter →
Then returns back to the tank
To add heat, I’m just redirecting the water after the filter. Instead of going straight back to the pool, I added a valve that lets me choose:
Regular pool mode
Or send the water through a propane heater first
Then it returns to the tank. That’s it.
The key to this whole system is a 3-way valve. No disconnecting hoses or reworking anything, just turn the valve. I can switch between pool mode and hot tub mode just by adjusting the valve.
The Heater
I used the same propane tankless water heater that we already have on our backyard outdoor shower. It’s inexpensive, portable, easy to hook up, and heats water quickly. If you already have one, there’s a good chance you can use it here too.
Tip: This setup works even better with a surrounding deck. I built a simple one for ours that makes using the pool so much easier, and I offer build plans to walk you through the entire build.
Materials and Planning
Tools/Materials I used for this project:
The build video walks you through exactly how everything connects, step by step. I’ve linked everything I used below to make it easy to source.
General Stock Tank Pool parts HERE
Main Line (1 1/2 inch PVC, schedule 40):
1-1/2″ PVC Pipe (cut into 3 inch sections)
1-1/2″ PVC MPT × Slip Adapter (threads into filter outlet)
1-1/2″ Slip × 1-1/2″ Hose Barb Adapter (connects back to plunge valve hose)
Heater Supply Line (3/4 inch):
3/4″ PVC Pipe (cut into 3 inch sections)
Garden Hose (Heater supply. Any hose is fine)
Heater Supplies (more detailed info here)
Heater Return Line:
This line runs from the heater back to the pool and includes a check valve to prevent reverse flow in pool mode.
Garden Hose (Heater return. Any hose is fine)
(2) GHT male → NPT male adapter (used to connect the hose to the check valve)
Check Valve (installed inline, arrow pointing toward the pool)
Flow Control:
Consumables:
Tank Insulation:
(3) Rug Pad (tank wrap insulation - long enough for the circumference of the tank)
Quick Note on Fittings
If you’re new to plumbing, the terms can sound intimidating — but they’re actually simple:
MPT = threads on the outside (Male Pipe Threads)
FPT = threads on the inside (Female Pipe Threads)
GHT = standard garden hose threads (seal with a rubber washer)
Slip fittings = glued connections
At the end of the day, it’s not at all as intimidating as it looks. You’re just simply connecting pieces to move water from point A to point B.
Insulating the Tank
If you’re going to do this, insulation makes a world of difference in both heating the tank faster and retaining the heat.
For the sides:
A wool or felt layer. I figured out that a 2 foot wide rug runner backing pad was perfect and easily accessible)
Paired with reflective insulation
Enclosed with waterproof outdoor fabric
For the top:
Rigid foam board (1–2” thick)
Covered with a good pool tank cover
How Much Propane Does It Use?
To heat my tank from 60°F to about 103°F I used about half of a standard 20lb propane tank. In my area, that’s about $10 per heat up. Of course this varies on outside temperature, starting warm up temp, insulation, etc.
Final Thoughts
This project turned out to be easier than I expected. It’s simple, relatively affordable, and lets you use your stock tank pool year-round. I also appreciate how all of the plumbing is neatly hidden under the deck. If you already have a stock tank setup, this is a really fun upgrade.
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