How To Build a DIY Cold Plunge Pool

DIY Cold Plunge Pool

DIY Cold plunge pool? I’m going to be totally honest, personally, I’m a hot tub guy and this blog and my YouTube Channel have lots of info on this. Freezing cold water is not for me! That said, there are many of you DIYers that are looking to build cold plunge pools. In this article I will cover what you need to think about in your designs.

First things first. The DIY Cold Plunge pools that I design are not modified bath tubs filled with ice or anything like that. They are full on “spa-like” pools that are chilled down using a physical chiller. They are filtered so are not single use and have water being turned over by a pump to keep it nice and healthy.

How Big Should a DIY Cold Plunge pool be?

The side of the cold plunge pool will really be dictated by how much space you have available but also how many people will be in the pool at once. Unlike a hot tub for example, cold plunge pools quite often are not communal areas and you would not be sitting in there with friends or family having a drink. Cold plunge pools tend to be smaller and can quite easily be designed just to be big enough for one or two people.

A smaller cold plunge will also be easier to chill down and cost less to run so that is something to think about.

In terms of the layout, it is quite normal not to have seating in a cold plunge. Again, it is the time that is spent in there, quite often being able to stand is better or in fact easier than sitting down in the cold plunge.

Cold Plunge DIY Kit
Cold Plunge DIY Kit

What should I build the walls of the DIY cold plunge pool out of?

Poured Form

Pouring a form is where you are creating a mould out of wood and then filling the mould with concrete to create your walls and seats. This is a popular way of constructing a cold plunge. If you do opt for this method, make sure that you brace the walls correctly as the last thing that you want is to have curved walls when you are done!

There is a huge amount of weight and pressure that is created when you pour the concrete so you need a lot of bracing in order for this to work. The end result is a perfectly cast cold plunge shape. This is a great way of doing things as you are embedding all your plumbing in advance so fitting the plumbing itself is easier.

You also get a good seal around all of the plumbing components so there are less chances of leaks when you use this method.

DIY Cold Plunge Pool

Type of Spa Construction

Concrete Block Cavity

One of the challenges of building a DIY cold plunge is getting the correct strength in the walls.

Concrete blocks are arguable the easiest way of building your hot tub. However, if you do a concrete block construction, you are going to want to have a cavity. This cavity will house not only the plumbing, but also the insulation and a rebar construction for added strength.

The downside to this method is that the final construction is quite wide, you can see the measurements below.

dual skin DIY Cold Plunge Pool

With a 4” block, 6” cavity and then another 4” block, you are at 14” as a minimum. With a. cap stone on this, this can look really good. Inside of the cavity you are going to house your plumbing, your insulation and your rebar. As shown below.

To complete the construction you will then fill the cavity with concrete and make sure it is well vibrated down.

DIY Cold Plunge Pool

CMU Block

CMU blocks are the hollow concrete building blocks you commonly see in construction. They are cheap to buy and do a really good job of creating a strong structure for the cold plunge.

You can see on the cross section drawing below that the metal rebar ties into the poured concrete base and also the walls too.

You should be rebaring every other hole so that all the blocks are tied into each other.

Once you have finished the structure, then you need to fill with concrete. The diagram also shows horizontal ties – these are optional.

CMU Block

ICF Block

Insulating concrete form or insulated concrete form (ICF) is a system of formwork for reinforced concrete usually made with a rigid thermal insulation that stays in place as a permanent interior and exterior substrate for walls, floors, and roofs.

The forms are interlocking modular units that are dry-stacked (without mortar) and filled with concrete. The units lock together somewhat like Lego bricks and create a form for the structural walls or floors of a building. ICF construction has become commonplace for both low rise commercial and high performance residential construction as more stringent energy efficiency and natural disaster resistant building codes are adopted.

ICF Block Hot Tub

ICF Block cold plunge

This is a quick and easy way of creating your hot tub or plunge pool. The structure and the strength are already there for you. The main downside is the cost. This is an expensive way of doing things.

In ground Cavity

I’ve done a number of projects of late where there has already been a hole in the ground that the customer wanted to convert into a hot tub. This is totally fine of course. Perhaps there has been a sunken plastic shell tub that you are replacing – this is when this kind of a method would come to light.

The drawing below shows what the construction would look like. You can see that there is a 6” cavity with a 4” block. The cavity will be filled with concrete once the plumbing is in place.

Which Method Do I opt for?

Ultimately, this is down to personal preference, material availability, skill set and budget. All of these methods I have highlighted above produce a fantastic end result. The cold plunge that you are dreaming of! However, each has their challenges so ultimately, you will pick the method that best suits you, your location, skillset and budget.

Cold Plunge DIY Kit

What plumbing considerations do I need for a DIY cold plunge pool?

Again, I’d like to point out that the DIY Cold Plunge Pools that I design are not just ice baths – they are fully filtered, chilled with a physical chiller and the water is turned over to make sure it is not a single use pool.

You will need a pump, a filter two inward suction drains and also two returns. These should be connected through a chiller

What are the health benefits of a DIY cold plunge pool?

Again, I’m a hot tub / plunge pool designer so I am definitely not qualified to talk about the health benefits. However, I did do some research for this article so thought I would include them anyway – just to be clear they are coming from much more qualified sources than me!

Cold Plunge DIY Kit

Why Should You Try a Cold Plunge?


There are several reasons why you should try out a cold plunge pool. First, it’s a great way to relax and unwind after a stressful day. Second, it helps reduce stress levels. Third, it improves circulation. Fourth, it reduces muscle tension. Fifth, it promotes better sleep. Sixth, it relieves headaches. Seventh, it boosts energy levels. Eighth, it strengthens immunity. Ninth, it helps with weight loss. Tenth, it improves digestion. And finally, it helps improve mood.

How Does a Cold Plunge Work?


The cold plunge pool works because water temperatures drop below body temperature. This triggers the release of endorphins, which are natural painkillers. Endorphins also help relieve anxiety and stress.

A cold plunge pool is a simple way to get yourself into shape without having to go to the gym. You simply jump into a deep pool of ice-cold water and stay there for at least five minutes. During this time, your muscles contract and relax, causing them to burn calories. In addition, the cold water stimulates blood flow throughout your body, helping to increase metabolism.

Is It Safe?


While there are some risks associated with using a cold plunge pool, these risks are minimal. In fact, the benefits of a cold plunge pool far outweigh any potential risks.

The first thing you should know about cold plunge pools is that they aren’t dangerous. There are many different types of cold plunge pools available, and most of them use water temperatures between 50°F and 60°F. If you choose to use one of these pools, be sure to follow the manufacturer’s instructions carefully. You should never leave children unattended in a cold plunge pool, and you should always supervise anyone who uses a cold plunge pool.

Cold Plunge DIY Kit

How Long Will It Take To See Results?


If you use a cold plunge pool regularly, you should see results within two weeks. However, it takes longer than that to see real changes in your body. You might notice an improvement after just one session, but it will take several sessions before you start seeing significant improvements.

The cold water shock helps to increase blood flow throughout the body, which improves circulation and increases metabolism. In addition, the cold temperature stimulates the lymphatic system, which helps remove toxins from the body.

Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi


Hi, Andi here. I own and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Today, I've helped over 1000 DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi

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