How to Build a Stock Tank Hot Tub for $657 (2024)

The coldest week of the winter—at least in these parts of the United States—seemed the perfect time to share our latest DIY project, which we just finished over the weekend. All the home renovation this past year has meant a lot of aching bones for these rapidly aging home renovators, so before Christmas my husband came up with an idea to build a hot tub out of a stock tank with a wood-burning fire, or a “redneck hot tub” as we like to call it, and while I was skeptical—you know what? It worked.

Disclaimer: Do not, under any circ*mstances, turn off your water circulation system without extinguishing the wood-burning fire completely. The water in the lines will turn into dangerous, vaporized steam that will scald you. Also, be safe when you’re burning anything. This project was a preliminary test case, and the images you’re seeing don’t reflect the safest method of controlling a fire. We intend to set the barrel on top of a much larger pile of gravel and bank the whole thing in with rock to prevent accidents.

Also, don’t mind the state of our deck in the below photos. If you recall, we discovered rotting joists last summer, had to rip out nearly the entire 1,000-square-foot platform and build a new deck from scratch. We had just gotten through priming and patching the nail holes when this cold hit, and now the surfaces haven’t had a chance to dry out enough. We need a solid three days of warmth and sun to topcoat it!

What it costs to build a hot tub

If you were to go to a pool supply store, you’d look at paying anywhere from $3,000 to $10,000 for a hot tub. My parents bought one the year we moved back and were living with them, and it barely lasted a year before it broke. It still sits on their back deck collecting dirt and pollen and mold. That was a really expensive item to basically just be able to use it for a season.

And while a stock tank hot tub likely won’t last us more than a couple years, it was fairly economical in comparison: It cost us under $700 in parts and an afternoon in labor. Here are the supplies you’ll need to build the stock tank hot tub that SVV conceptualized:

Project cost: $657

But before you just take what we say as gospel and buy all of the above parts, let us tell you why we did what we did to make sure it works for you.

Why you’d want to build a hot tub out of a stock tank

Most people love the idea of having a hot tub and fully intend to use it on the regular, but we all know that the novelty wears off with the passage of time. The direct costs of running an electric heater and pool pump to keep the body of water inside a hot tub at the right temperature and sanitary enough for bathing are very high, and the chlorine chemicals wafting up our nostrils have never been our cup of tea for a relaxing spa experience.

SVV was inspired by the thought of creating a setup that could use fresh water without chemicals and that didn’t require a monthly electrical bill increase. In addition, he’s always trying to think of ways to repurpose single use things like this and so thought that having a hot tub that could be used in the summertime as a plunge pool from the often oppressive heat of the South would be a great way to do that.

Repurposing the stock tank

A big draw of the stock tank is that we can use it as an ice tub or cold plunge pool in summer months. In fact, we love the concept so much, we’re going to buy a couple additional ones to use as planters or a water pond, and swap the pond pump into the system when it’s not being used as a heated pool.

Tools you’ll need to build a hot tub

These are the tools we used to put the hot tub together. If there’s a big tool you don’t own or can’t borrow from a neighbor, you can always rent one for the day from your local equipment rental company. Though, that said, these are all tools in our kit that get a lot of use, so if you are a home renovator, we can’t more highly recommend the following:

All of the above can be purchased at your local Home Depot or Lowe’s, and if you’re not going inside any stores right now (which, good for you!), I’ve linked everything we own above to items that ship for free with two-day delivery, meaning you could have everything and build this hot tub bad boy by next weekend if you like.

Putting the hot tub together

We got the stock tank a few weeks ago at Tractor Supply. No pre-ordering necessary, at least not where we live in horse country, and it cost just shy of $200. Since we’re a household of two, SVV settled on an oval size that perfectly fits the two of us. If you’re a family, you might want to get the circular model instead, which will cost a bit more. They sell an 8-foot-by-8-foot galvanized tank for $430, for example.

Earlier in the week, we first primed the sides of the tub with an oil-based red-0xide primer, a great product that is made by a variety of manufacturers. This step will help prevent rust and corrosion and is a good base coat for almost any metal. Despite the cold, it dried pretty quickly, and we were able to put the first coat of paint—Sherwin-Williams’ Tricorn black as always—on that afternoon, then do the final topcoat the day after. This step is crucial in making sure your stock tank hot tub lasts at least a few seasons, so start the priming process a few days before you want to use the hot tub so it has time to properly cure. It also looks a lot better with some paint over the shiny metal.

We couldn’t find the pump locally, so ordered it from Pond and Garden Depot, and it came in within three days. SVV probably over-engineered the pump and hose setup (1800 gph and 50 feet of 3/4″ flexible pond hose), but there is a seven-foot lift that the water needed to do and the more powerful pump ensures that we can locate the burn barrel almost anywhere away from the stock tank. Once we had all of the parts, it just took a couple hours this past Saturday to put the hot tub together and test to see if SVV’s concept would actually work.

To start, he bought a couple of steel drums from a local guy off Craigslist at $20 a pop, then took a grinder to one of them and cut out holes at the bottom of the barrel so the fire could breathe. This wound up being a bit too much, so if we were to do it again, we would only cut two holes or make them smaller. As it is, we had to block a few of the holes with rock upon lighting the fire because it was stoking the inferno far too much, and it required constant attention.

Next up, you’ll need to retrofit the 60 feet of 3/4″ copper coil to the barrel. This proved to be the most challenging part, so in the end, we flipped the barrel on the side, I sat on top of it to hold it down, and SVV coiled it so it would fit nicely within the barrel. Bonus: Now we know how to make a still if ever distilling becomes a side hobby! Also note, this system would likely work with 1/2″ copper coil (cheaper) and a smaller pump, but my husband likes to make things bullet-proof, so if you’re that type of person, go with the 3/4″ piping throughout the system.

The copper comes pre-coiled, but it still needs to be shaped by hand to fit inside the 55-gallon drum. The soft metal is fairly easy to manipulate just be sure to not kink the tubing, as this will create a failure in the integrity of the water system. Once the coil was shaped to his satisfaction, we ended up with one end sticking out of the top and one end sticking out of the bottom.

To tie the system into a plastic water line, you’ll want to extend them with a piece of straight pipe, and a 5-foot section cut in half works perfectly for that. Each end of the barrel will need a copper adapter piece that has a threaded end so you can hook up a barbed fitting. Soldering copper is a skill set that SVV already has in his arsenal but there are many videos out there on the internet to walk you through the process. Be sure to polish the ends with sandpaper for a good seal, be safe with the blow torch, and do it all outside.

Then, it was time to carry our barrel to the backyard and place it near where the hot tub would be. We will likely extend the water lines another 20 feet each to get the placement just right, but having the fire 25 feet away seemed just about right.

Starting your wood-burning fire for the hot tub

Now you’re going to build a wood-burning fire as the heating mechanism for the hot tub. Steel barrels like these are super efficient for starting and maintaining a good blaze, but it takes practice to figure out how your setup will work.

The coils collect heat from the flames as the water circulates through the copper and pond hose system.

We did a test run, thinking it would take hours to heat—particularly the first time—but in under 30 minutes, the water was not only hot enough to use in freezing weather, but too hot.

Which brings me to this: Be careful and heavily monitor your water temp at all times! On the second run, we figured out the precise amount of fire to maintain a pleasant 104-degree temperature, but the first run was a straight up incinerator.

Some safety tips

Obviously, we’re talking about fire here, so proceed with caution and don’t let your kids and pets near the barrel. Since you’ll be self-regulating the temperature, consider buying a sturdy pool thermometer for $15 and keep it near the water inlet coming from the barrel. So far, we’ve used a kitchen thermometer, and the hot tub stayed right below 105 degrees without us needed to adjust it, but this also is because the combination of outside temperatures, length of hose and size of the fire just happened to line up. There are a lot of variables so be prepared to make adjustments and have a garden hose handy to add cold water or extinguish the flames as necessary.

Do not remove the suction pump from the stock tank if the water gets too hot! This will create the aforementioned scalding steam since the water won’t be circulating anymore. Either extinguish the fire, add water or simply wait until the temperature is right

We’ve had the hot tub since Saturday and used it three days for a quick dip or happy hour. Now, I just need SVV to make me a pair of height-appropriate side tables to house my bourbon.

Any questions? Ask below, and we’ll do our best to answer!

For other DIY projects, see some of our more popular home reno posts:

How to build a dog ramp for under $30
Painting a bedroom like a pro
How to paint the exterior of your house
Building DIY planters for your garden

This post contains affiliate links to the parts we used, though all products were purchased by us.

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