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 SVV 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 circumstances, 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:
- Stock tank, $190
- 55-gallon steel drum, $20
- Copper fittings, $20
- Copper pipe, $150
- Pump (1800 gph and 50′ 3/4″ hose), $265
- Spring clamps (pack of four), $12
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.
Just call me Beth Dutton. Funny enough, we’d been planning this stock tank hot tub project before watching Yellowstone, yet I’m happy to be in such company as the original BA Beth!
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.
If you live in a home with a small backyard or limited storage, this is a great option for you as it’s something you won’t just use in the winter months and if you have a garage, other than the barrel, you could easily store the whole shebang in a corner.
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:
- Grinder, $45
- Blow torch, $26
- Pliers, $48
- Safety glasses, $22 for a 4-pack
- Ear protection, $5
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 for SVV? Ask them below, and I’ll make sure he answers!
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.
How clever! Heading somewhere warm soon but keeping this in mind for my next trip back to NJ during cold winter months. Meaning, winter 2022 😉
It definitely helped us get through the bitterly cold February that we weren’t expecting!
Wondering if I could use my blue poly stock tank with this or very similar setup.?
I know some people like the enjoyment of building stuff but have you heard of an inflatable hot tub?! My husband got me one for Christmas in 2019 and it’s been glorious, and the price runs between $450-600 depending on demand!
I had no idea that was a thing! This was definitely fun to build, but the process isn’t for everyone 🙂
Amazing creativity guys keep it up.
Thank you! It was a fun project to hack, for sure.
Where does the pump go?
The pump stays on the ground. We prime the pump with water, then it sits on the ground and the two lines, the intake and output, come out of it.
The pump probably is of equal efficiency wherever it’s placed. But maybe lasts longer if placed before the cauldron of fire.
Hi, I love this set up, it looks so great! What type hoses are those that you have attached to the tub?
Thank you so much! It’s a pond pump we got from a pond supply store online. We’ve been using it as a water feature in the summer months with water plants like lily pads and frogs. About time to bust it out for winter again!
How do you keep the pipes from freezing when you’re not using it? I would think they would burst.
Hi Brian! It’s an “open” system, in that the flexible piping that runs from the pump to the tank and to the 55 gallon barrel heater isn’t a complete seal like home piping, which ties into city pressure. If it were a “closed” system it absolutely would burst when the temps drop below freezing.
That bit of give removes the potential of busted pipes. The flexible nature of pond hoses also help
Did you use flex seal or any sort of leak seal on the inside of the tank to prevent rust? Any suggestions on this? I have an old stock tank that we removed any rust from but want to prevent it coming back with water sitting in it?
Hi Lindsay! We don’t use a leak seal in the inside at the moment. I think in the future if rust starts to appear (it hasn’t yet) I would prime the entire inside with red oxide paint, which converts the rust and prevents it in the future.
Then, I’d topcoat the red oxide with a product like Sher-Cryl. It won’t last forever but should be good for at least a season or three. Also, we don’t use chlorine and instead fill it each time we use it, which will also keep the rust at bay. Let us know if you do it!
Curious what barbed fitting did you find fit the hose. They seem to have a weird interior measurement that 3/4 don’t fit.
We live in the outback of South Australia and love the look of your stock hot tub ,do you have a instructions booklet on how to complete this project as we would love to have a stock hot tub for this up and coming winter.
Thank you in advance
Sheila and Rod McGregor
We were going to use a stock tank as an outdoor soaking tub-we have hot water from an outdoor shower nearby. My question is about draining it- how do you get the water out all the way so it’s empty? Do you drain with a hose so you can control where you put the drained water? Also did you build a cover and if so how?
The stock tank has a fitting on the bottom and I attached a short length of hose and a valve. This makes it easy to drain and if needed, I could attach a hose to release it far away (it just goes into the grass around it now.
Did not build a cover and I don’t think it’s necessary. We just wash it out real good before filling
do you usually re-use the water? do you use something for keeping the water clean? I can’t realise if it’s a big waste of water or not! thansk in advance!
Awesome!! I was looking for how to do this and thank you!!
I have two questions. What are the dimensions of your tank? Did it come with the drain or did you drill and install that yourself?
That is so clever of you to do that. Loved it.
Is the pump necessary in circulating the water through the copper lines? I hadn’t seen anyone else using a pump for their builds and was just curious before we did this project.
Jake, yes! The hot fire around that copper will turn the water in the lines into very dangerous pressurized steam if it doesn’t circulate. As it is, you’ll quickly find that the water will get hot fast and you’ll need to douse the flames or re-route the fluid into another container.
This is an awesome idea, and after this brutal winter here in Michigan, I could certainly use one right about now!
Next on my list, a stock tank hot tub 🙂
– Sara Billings
I really enjoyed this article. We have been considering a hot tub for a while now but didn’t want the huge manufactured units due to a limitation of space.
I do have a question. As I read your article, I wondered what heat sources I could use that wouldn’t require open burning or a source of wood. One that came to mind was a propane tank heater with the heating element somehow inserted into the barrel. Did you consider other heating sources when you were building your tub?
Hi Dave! Yes, I did consider different heat sources. The one that intrigued me the most was a hot tub heater (duh, right?). They’re inline and attach to a pump. I’m pretty sure that it was out of my price range but that’s totally an option if you don’t want to use fire for the heat.
I think a propane heating element would work, as well, but I haven’t researched that. Something from an RV supply, perhaps?