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Build your own chest freezer ice-bath

At the beginning of 2021, I was in the final stages of preparing for one of my most significant swimming challenges to that point - a crossing attempt of Foveaux Strait. The Foveaux Strait lies between Stewart Island and the South Island of New Zealand and, for anybody that is not familiar with this body of water, it is notorious for two things: 1) cold waters, and 2) an abundant great white shark population. One of those things I could prepare for (and no, it wasn't the great white sharks!).

At the time, Auckland coastal water temperatures were sitting a comfortable seven degrees Celsius above what I was likely to encounter in the Foveaux Strait (around 14 degrees Celcius). That may not sound significant, but it certainly is when you are likely to spend more than seven hours with most of your body submerged at those temperatures. So, to prepare, I did something that was quite unorthodox at the time in the New Zealand open-water swimming community: I bought a chest freezer and proceeded to convert it into an ice-bath.

Of course, I received a number of sideways looks at first. But over time, other swimmers have come around to the potential benefits of using a chest freezer ice-bath as part of preparation for a cold-water event. Use of my home ice-bath setup was extremely personally beneficial in the lead-up to crossing the Foveaux Strait, and it has been even more so during the build to other challenges of significance in extreme temperatures. Later that same year in 2021, I also completed my first Ice Mile - a mile of swimming in water less than 5 degrees Celsius. I credit the ice-bath for the sharpness of my body and mind in taking on this challenge. There is nothing quite like enduring an ice-bath at 3 degrees Celcius for an hour to really push you to your mental and physical limits.

Since setting up my own ice-bath, I have had plenty of people approach me and ask about setting one up for themselves. This isn't a blog post to talk about the benefits of cold-water immersion (I previously wrote on the benefits of cold-water swimming here) - this post is to provide you with a step-by-step guide to building your own chest freezer ice-bath. This is a relatively simple setup, but it has worked really well for me.

Reading in a chest freezer ice bath

Straight chillin'

Materials you will need:

  1. A chest freezer (estimate: NZD400-500) A second hand chest freezer will do the trick fine. Mine is around 280 litres and is certainly on the smaller end of the scale. I am 5'8" and am able to submerge fully only if I position my body on a certain angle. I would generally recommend a chest freezer with a capacity of 350 to 400 litres. I bought my chest freezer from TradeMe (a New Zealand buy/sell site), complete with a few bumps and scrapes. A new chest freezer is not necessary, so whether you buy used or new is down to personal preference. I would also recommend going for a chest freezer that has a flat lining as opposed to a textured lining. This makes it easier to stick things to the lining; for example, the suction cups of the internal water filter.

  2. A bung/plug for the drain hole (estimate: NZD10) I bought a basic rubber bung from the local hardware store and shaved it down to size to fit the drain hole for my chest freezer. It does the trick perfectly and keeps water from leaking out of the drain hole unintentionally.

  3. An internal water filter (estimate: NZD80) When I first started on the journey of setting up my chest freezer ice bath, I went about buying an external canister filter - bad idea. Unless you are savvy with putting holes through the wall of your chest freezer, an internal water filter is definitely the way to go. These water filters are fully water-submersible and will help to clean your chest freezer of debris as you go. This internal filter by Aqua One is the version that I recommend for anybody based in New Zealand, largely for reason of availability. There are also some good options on Amazon that are designed for higher capacity aquariums if you fancy waiting a bit longer. I have heard good things about the MarineLand Magnum Polishing Internal Canister Filter but have not tried myself.

  4. A temperature controller (estimate: NZD80) A temperature controller will help to control the temperature of your chest freezer within the desired range, regulating power supply and keeping the chest freezer from icing over (or going too warm). I went with the INKBIRD ITC-308-WIFI temperature controller. It has certainly served its purpose, keeping the temperature well moderated. The power supply for the chest freezer hooks into the temperature controller, and will turn on or off as it reaches the low or high set points, respectively. The temperature controller also has WiFi capabilities, allowing you to control all settings from a distance if you fancy.

  5. A surge protected powerboard (estimate: NZD20) A basic powerboard allows you to have all your cables plugged into the one place. You can find a surge protected powerboard at your local hardware store.

  6. Waterproof silicon sealant (estimate: NZD20) I went with Selleys Wet Area silicone sealant, but any similar product from a reputable brand will do the trick. Just make sure that you are buying the waterproof version because it will certainly be getting wet!

  7. Zip ties or cable tidy (optional) There will be a few cables lying around, and so a zip tie or two will help to keep them all tidied. Whether you use zip ties, a cable tidy, or nothing at all comes down to personal preference alongside potential safety considerations (for example, if you have an overly curious pet/child).

  8. Bath mat (optional) This is an optional, but certainly a practical optional. You will undoubtedly get the surface you step on wet as you get out of the bath. Any bath mat will do, but absorbent is certainly helpful.

  9. Wooden step (optional) Depending on how tall (or not) you are, a wooden step can help you to get in and out of the bath without overextending your legs. I do not have a wooden step in my setup.


Now for the fun part, where we bring it all together.

  1. Place your chest freezer in the desired area of your home/garage.

  2. Seal all cracks and edges on the inside of the chest freezer with silicone sealant. If you are inexperienced with applying sealant, there are plenty of videos on Youtube to help with this part. Leave the silicone to cure before adding water.

  3. Install the bung into the drain hole. I prefer to use a bung over completely sealing the drain hole, so that I can use the drain hole for flushing the water.

  4. Plug the chest freezer power supply into the temperature controller and test.

  5. Plug the temperature controller and internal water filter into the powerboard. Test the temperature controller but wait until the internal water filter is fully submersed before turning this on.

  6. Place the internal water filter in the chest freezer at a mid-level height.

  7. Test the seal of the chest freezer (in particular, the drain hole) by adding a small amount of water.

  8. Once you are happy that the chest freezer is not leaking, fill the chest freezer with water to the desired height. You may need to play around with this to get the levels right. Remember that you will be displacing a large amount of water once you hop in, so you don't want to fill it too high.

  9. Submerge the thermometer in the water and program the temperature controller to the desired settings. I have mine with a low point of 2 degrees Celcius, a set point of 3 degrees Celcius, and a high point of 4 degrees Celcius.

  10. Leave for 24-48 hours until the water reaches the desired temperature.

  11. Get in and enjoy! (But remember to turn off the power to all devices before you do. The powerboard comes in handy here.)

Chest freezer ice bath

My humble garage setup - and yes, I do watch movies from the comfort of my ice-bath

Temperature controller

The INKBIRD temperature controller in flight, with a current reading of 3.6 degrees Celcius

There are two outlets for the power supply - I'm sure you can figure out which is more appropriate

I leave the thermometer dangling over the edge - a crude but effective solution

The water filter in action (Note also the colour of the water and debris. Definitely overdue for a flush!)

A few notes on maintenance:

You will see that I haven't recommended any form of water sanitation (for example, chlorine or bromine). This makes for a more straight-forward setup, but it also means that the water will spoil more quickly. Depending on usage, I recommend flushing the water and replacing every 6-8 weeks. You will get a feel for when it needs to be replaced due to the colour (and, at times, smell) of the water. When the water starts to take on a green tinge, it's probably time to flush.

Most chest freezers have a drainage hole which allows a hose to be plugged in. This is really handy and makes the flushing exercise quite straight-forward. Once you have firmly plugged the hose into the exterior drainage hole, you can release the bung which plugs the interior drainage hole. There is often a very small amount of residual water at the bottom of the chest freezer after the hose has done its part, which I have tended to remove with a few towels. Once the chest freezer is fully drained, it's a good opportunity to give the walls and bottom of the chest freezer a good clean before refilling.

The internal water filter should also be removed and have the canisters cleaned every 1-2 weeks; again, depending on use.

Other than that, it is a very simple and cheap toy to maintain.

I look forward to hearing your stories about your own chest freezer ice bath setup. I'd love to know how you get on - drop me a comment below!


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