Having a DIY plunge pool in your back yard doesn’t get any better in those hot summer months! Did you know however, that they are easier to build than you think? In this article we are going to look at all the different variables you are going to need to consider to build your ultimate DIY plunge pool. Don’t worry, as I have already said it is easier than you think.

Planning, Planning and more Planning

Planning is key. If the planning stage is done correctly, it will make the rest of the build much easier.

I learnt the hard way by not planning to have enough space for my “control room” as I call it which is where your pump and electronics go; we’ll look at this later in this article.

Let’s take a look at the variables.

Location

So where are you going to put your DIY Plunge Pool? You might not have the advantage of numerous likely areas in your backyard, however in the event that you do, here are a couple of things to consider.

How are you going to fill it?

Obviously, your Plunge Pool will require water and it will require topping up consistently (due to evaporation and loss through bathing suits) so you need to have a water source eg tap close by. Sure, you can run a hose, however, it doesn’t look half as good if you build your fill pipes into the build itself so that they are not visible.

How are you going to empty it?

You are going to need to do this a couple of times a year minimum to make sure your water is nice, clean and healthy. With the volume of water and chemicals, you are not going to be watering your flowers with this water!

So, the question is where is your nearest drain and how are you going to get the water into it? You could use a submersible pump and a hose, or you could design in the drainage plumbing into the system. Again, these are things that you are going to need to have a think about before you break ground.

What do you want to look at when you are in the tub? Is there a view? Perhaps this may seem an odd point, but if you do have the option of a view, you really want to take it as opposed to looking at a wall! This can also potentially affect where you place the plumbing. This is one of the beauties of designing your own plunge pool – you get to make it just perfect for you and your location.

Where are you going to locate your “control room”? Pumps, pipes, filters, all take space and need to have it allocated and allowed for.

You are going to need electricity to your tub one way or another and we will look at this later in the article. Where is it going to “plug in”? More a case of course, where is this going to be wired into as there are no plugs per se.

What landscaping are you planning. Do you need space for a deck around your Plunge Pool or space for steps. Lots of things to think about on the location but most of these will depend on where you are planning to install pool.


DIY Plunge Pool – Above ground or in ground?

This is a crucial question as it will affect the design of your tub. Personally, I prefer in ground as I want things to be as minimal as possible in my garden. I also liked the idea of dropping into the ground rather than “being on display” for all the neighbours to see. You also need to think about your brick or block laying skills and whether they are going to be up the the pressure that the water is going to create. There will be quite a bit of water in your plunge pool and if your brick work gives way, that will spell disaster!

External Roof or Indoors?

Are you planning on building a roof over your Plunge Pool or even a full building? This is the time for making all these decisions and plans as the later you leave it, the harder changes. Things like positional footings would have to be considered at this stage, not something you want to be adding afterwards.

Physical Dimensions & Design

How big is your plunge pool going to be? How many people are you wanting to have in it at the same time. How much space do you have available in your backyard or location. These are all things that you need to consider. The dimensions also will affect things like the size of the pump and heater (if you opt for a heated plunge pool) so they are really important.

How deep should the seats be? What about the footwell depth?

These are things that I can certainly help you with and are part of the consultancy that I offer for free when I supply you your plunge pool plumbing kit that we put together on a customized basis.

Materials

What are you going to build your Plunge Pool out of? I am sure you have already had a look around YouTube where you can find some interesting videos for pools made of “shotcrete” or “gunite”.

These are really cool to watch and they involve the pool or spa to be formed with a metal rebar structure. The piping and plumbing is then attached in place to the rebar and the whole thing is filled with concrete that is sprayed in at high pressure then skimmed flat. For us DIYers, this is not an option. Very cool, but requires a lot of skill that even those of us who think we can do anything (me!) should stay away from.

There is a simpler option. I opted for blocks, concrete and mortar and would highly recommend this method. As a newbie to brick laying, firstly it works, I’m testament to this and it wasn’t overly difficult. The other thing I was able to do with this method was use lots and lots of concrete. Being a first time brick layer, I wanted to make sure that the structure I was creating was going to withstand the pressure. Being able to backfill behind the blocks (if you remember I opted for in ground construction) gave me total peace of mind that I was going to create a very strong structure.

Bricks incoming!

The other thing you need to think about is what finish you are going for. It is totally possible (and cheaper) to skim the tub over with a waterproof concrete render, and then paint it with a waterproof paint. Are you considering the swimming pool approach with the small tiles? Fiddly, but they do look nice.

Or, are you considering something like the finish I went for which was waterproof floor or wall tiles. I also went for quite large tiles to minimise the about of joints and grouting needed. You don’t actually need specialist tiles as long as they are waterproof and suitable for walls and floors, you should be able to use them.

In regards to materials, at every stage ask yourself how is this adding to the waterproofing of the pool? Every element needs to be adding to this. You should be adding water proofing agent to your mortar for laying bricks, waterproofing agent into your render, some form of sealant over your render (I used PVA) and then if you are using tiles (which we have already established should be waterproof themselves) both the grout and adhesive need to be swimming pool grade which is waterproof too.

DIY Plunge Pool Shape

What shape are you going to opt for? Remember, this website is concentrating on building using concrete blocks, they are square! Most of your shop bought tubs are cylindrical. It is certainly easier to make a square tub using cinder blocks, and they are quite easy to cut with the right saw (15 quid ($15 USD) off Amazon) so you could create a hexagonal or a more ambitious shape if you wish. Do remember that you are potentially going to be tiling this too so the more ambitious the shape, the more difficult the tiling is going to be. Food for thought.

Plumbing, Lighting and Audio Visual

At this stage consider underwater lighting (yes you should as it looks really cool check out the light we supply) and any other Audio Visual components you are thinking of having. For example, do you want speakers and some form of Bluetooth system for sending audio from your phone?

Build a DIY Plunge Pool

One of the things I would like you to think about at this stage is where is the skimmer going to go (This is the top filtering element where bits of debris from the surface drop into a basket so can be removed) and also where are the two bottom drains going to go. You need two so if one does get blocked, it is not going to ruin your pump. Incorporate these into your design now rather than later. Certainly, this should be done before you break ground.

Plunge Pool DIY

Plunge Pool DIY

Plumbing

After the physical integrity of the Plunge Pool structure, the plumbing is probably the next most import part. After all, without the plumbing, you don’t have a Plunge Pool. As an overview, the concept of a Plunge Pool is pretty simple. Tub is full of water. Water is flowing through the skimmer at the top and through the drains (drawn in by the pump inlet) at the bottom. Water flows from skimmer and drains into the filter, from the filter into the heater if have chosen to have one. From the heater or directly into the pump and from the pump out back into the pool. The concept is basic right? Correct, it is not a difficult concept. However, there are a few challenges to get to this point.


Types of Pipe

Pipes come in all shapes and sizes however with DIY Plunge Pools, there are two sizes and two types. Firstly, there is rigid pipe and flexible pipe.

Now, do not kid yourself here as the “flexible pipe” is not flexible! Yes, you can bend it a little but is very hard and you will not be tying any knots in it.

This was a mistake that I made as my life would have been made easier if I had used some 90 degree junctions rather than trying to bend pipe. I had flexible bent pipes coming up through the steps from the bottom drains. I was trying to minimise joints as I thought that more joints would potentially mean more leaks. However, I was wrong on this as the pipe and connectors are so well made that an almost perfect joint is made each time with plenty of PVC pipe cement you will be all set.

Keeping the pipe neat and running parallel with good joints leads to lowering the probability of leaks. In my case, I knew exactly where the first leak was going to be as I ended up with an overly complicated joint on a funny angle that I couldn’t quite get to in the “control room”. Low and behold, when I filled up that was the first leaking point. I’ll talk later about what I used to fix leaks as I tried a few products and they didn’t work. OK, so back to our flexible pipes. These pipes are pressure rated so they are not the same as household plumbing pipes.

I used Waterway pipes in my construction (again one of those American brands) and they are really well made pieces of kit. There was also pretty much every combination of connector, bush or corner piece that I could think of. The pipes went together and felt so solid and well made I would definitely recommend Waterway pipes. I’m sure other brands are just as good but I only have my own experience to draw from on this point.

I mentioned that there is also rigid pipe available. I’ve no evidence for this but my thought was that if the pipe was flexible then it would be able to cope a little better with the pressure and would be less likely to pop out of a joint, so I opted for flexible. Its a little bit more expensive but in the whole bigger picture of cost, it is not going to break the bank.

Plunge Pool pipes, as well as being pressure rated are a specific size. Water pipes are 2” in diameter. This is different from swimming pools. Also, something to note here is that an imperial 2” pipe is NOT the same as a 53mm metric pipe. At first glance it would look as if they are as it is hard to see the difference. However, there is a difference of a millimetre and a bit.

This does make a difference when you are trying to make water tight joints that are going to hold under signigicant pressure. Make sure that the parts that you buy all match. With Waterway what I will say is that they do have adaptors to take you from 53mm pipe back to the 2” as I used a couple of them on the skimmer. I’ll talk about this next.

The Skimmer

You now need to consider the Skimmer’s position. This is a little more tricky than you might think. Firstly, you want to have the skimmer as close to your pump in the “Control Room” as possible. Secondly, the height of the Skimmer is going to dictate the water level. The ‘perfect’ final water level in the Plunge Pool is that it comes half way up the skimmer. This is to allow any debris to flow freely into it where larger pieces of debris, or in my case, usually the kids toys, end up in the basket. Smaller leaves and bits pass through and are caught in your filter.

Plunge Pool Skimmer

The other thing that you have the consider with your skimmer is the final top position of the access grill. This was something that I got a little bit wrong on two cases. Firstly, I under estimated the overall height of the skimmer when I had added a 90 degree bend on the bottom to direct water towards my pump. For me, this meant getting out the hammer drill and having to break another 20cm (8″) of concrete that I had laid so that it would fit. Secondly, I also got the height a little wrong so it doesn’t sit flush with the deck that I have put in afterwards. It wasn’t a big deal as I made a cover to fit but in a perfect world, it would have been flush.

The size of the skimmer that you choose is going to be dictated by the size and volume of water you are going to have in your tub. Check with the manufacturer for what they suggest. I have 2800 litres which has meant that I needed to opt for a swimming pool skimmer. I went with a brand and choose the Certakin brand as they are the ones that you regularly find in swimming pools. My tub was too large to consider a Plunge Pool one. This posed a couple of difficulties. One was that it was actually on the metric sized 53mm pipe and I was of course on the 2” water. A bush and 90 degree bend from Waterway sorted that out.

Pump for your DIY Plunge Pool

We’re now getting to the expensive components of your Plunge Pool so it is worth taking some time to get all of this right. Let’s start with looking at pumps. For a plunge pool as it has no jets, you are just looking for a circulation pump. Something with less than 1HP is more than sufficient to circulate the water through the filter.

The filter. This is essential to keeping that lovely large body of water nice and clear of debris and bits. With the filter, these are sold by how many litres an hour can flow through it and also the size of the body of water you plan to filter. The bigger your Plunge Pool, the bigger the filter required. Makes sense really. Filters are made up of four elements, Cores, Media (Filtration Fabric), Bands, and End Caps. What you want to do is make sure that the filter has a properly designed core that maximises the filtration area. This in turn increases the flow and it will also create a uniform flow through the entire cartridge. What this means is that you will in effect increase its life and the cleanliness of your Plunge Pool water. Top tip, don’t skimp and buy cheap here. Buy a good quality filter from a reputable manufacturer.

When you are choosing your filter, you need to be mindful of the pump that you will be using too. I choose a Waterway filter and a 50sqm one. That matched up with the size of my Plunge Pool (7.5ft x 6.2ft approx) 46.5sqft. So on those calculations I am at the upper limit of the filter really once you allow a little bit for water head.

However, one of the features of the Waterway filter that I chose was that it had an auto bypass for high pressure. This means that under regular circulation pressure it will filter my tub.

From what I have found online, over specifying your filter is not a bad thing and it can reduce potential expensive damage to your pump if the pump us put under undue pressure due to a restriction of flow through the system. So, if you are not sure, then you can go up to the next size if you need to.

Plunge Pool DIY

Plunge Pool DIY

The Spa Pack

There are a few things that you need to consider when you are selecting your Spa Pack. You do need to have some controls for your filter cycles and using a Spa Pack in your plunge pool is way way of doing this. If you are going to heat your plunge pool at all, this is the way to do it.

Firstly, is the heating element and the power of the heater. The heater that you need is going to be dictated by how much water you are looking to heat. I’ll use my own example here and I have 2800 litres of water that I need to heat.

Plunge Pool Spa Pack

My tub at 2800 litres is quite large and it does take time to heat. I opted for a 3KW heater and from cold, it takes 40 hours to heat. To recover, which is after you have used it, how much temperature you loose, I’m looking at 0.5 degrees an hour. When I’m using the tub, if I’m in for an hour, I’ll loose about 3 degrees so it is a further 6 hours to heat it back to temperature.

Now, if I wanted to speed this up, I could have put an independent thermostatically controlled slave heater in and double the size to 6KW of heat which would in turn speed things up. I think fluid dynamics is not a straight line so I will not say that it would be twice as quick but it would speed things up. These are the again decisions you need to make at design stage or leave enough space at design stage so you can retro fit if you need. I’m fine with the 3KW and now that I know how long things take I can plan accordingly.

For me, the absolute must was WIFI control. I love gadgets in general but from a practical side I wanted to be able to control the spa from afar. Set it heating up if we are away and monitor the temperature. I knew that I wanted a Balboa Spa Pack and opted for the WIFI enabled BP601. For the topside controls, this really depends what you want. I know that some people now don’t bother with them and just use the WIFI. I however did want some control just in case the App or WIFI had any issues and went for the TP400 a simple but does the job control. I can’t stress enough to look at the specifications as I’ll explain shortly how my not paying attention to specs has cost me in the wallet.

Lights

Having a light in the Plunge Pool is must. It adds to the atmosphere, means you can use it at night and it really looks the part too. Out of all the parts of my build, I expected the light to be the easiest. Yes, it was simple to fit, but has caused me some problems which I will come on to. Because of the size, I wanted to go for a swimming pool sized light. I chose a large LED multi-coloured one which I thought would look great and it does by the way but not without causing me problems.

In order to make things easy for the DIY plunge pool, I’ve launched my own light that can be used on your build. Check it out here.

The “Control Room”

The “Control Room” as I call it is where you need to house your pump, Spa Pack and filter.

The next thing for the “Control Room” is make sure it has a drain! You don’t want this to fill up with water (believe you me, I’ve don’t it and it is not pretty) The expensive components are meant to stay dry – fact! You need to make sure that your Control Room can drain if water does escape, which it will, when you change the filter or when you remove the pump for a service. It needs to drain away. I put a piece of pipe in the bottom of mine so when I lined it with concrete, I removed the pipe once it was dry and there was a hole onto the dirt for the water to drain away. I know some people also put in a water pump with a floatation switch into the control room so if it does fill up, the pump will kick in. This is fine, but it depends just how quick things fill up.

Electrics

When you are planning your Plunge Pool electrics, it is important to take into consideration the electrical requirements. Most of the time, this is one task that you are going to need to get a professional in. Doing it yourself is dangerous and can also, in some cases, void insurance policies and the like. That said, it is important to understand what you need to ask your electrician to do for you.

Firstly, you need to have, or it is recommended that you have your own breaker. This basically means that on your fuse board, you have a dedicated fuse that is just for your Plunge Pool. If the Plunge Pool trips the fuse and turns off, the rest of your house is left on. This is how it should work.

The size of that breaker or fuse will depend on the kit that you put into your tub and we’ll look at that later in this article.

Dedicated Outdoor Rotary Switch

Durning the planning stage of your Plunge Pool, you should consider where you are going to place the outdoor rotary switch. This is the switch that in the case of an emergency, you can turn off and kill the power to your Plunge Pool. A key component in Plunge Pool electrics.

This is simply a rotary on/off switch but should be sited more than 2 metres (6ft) away from the Plunge Pool so that bathers cannot be in the Plunge Pool whilst touching the switch.

Plunge Pool electrics

The electrician should fit a suitable weather proof block connector to the end of the tail from the isolator, the Plunge Pool supply can then be directly hard wired into the weatherproof block connector inside the Plunge Pool. Waterproof gland packs should be used to prevent ingress of water on all electrical connections (2 at the isolation switch). Ensure that all earth cables are clearly colour coded with green/yellow insulating tape or earth sleeve.

The size, or current rating in Amps of the switch will depend on the kit that you put in your Plunge Pool.

Outdoor Cable for Plunge Pool Electrics

When you are running cable from your fuse board to your rotary switch and then out to your control room, you need to make sure that you are putting the right gauge and type of cable.

In order to deliver the correct amount of current and not overheat the cables, you should be as a minimum putting in 10mm cable as this should be rated for up to 65 Amps.

The 10mm size is the cross sectional area of the individual live or neutral wires. This is not the combined cross sectional area. This bit is important as if you put wire that is too thin in your system and draw too much current along it, they will overheat and in some cases, will actually melt! Hence the need for a qualified electrician. You should be asking for cable that is capable of delivering 65A.

Armoured Cable

If you are running cable outside, for safety, it really should be armoured cable. This means that if you accidentally stick a garden spade through it, you will not get through to the cable and will not get an electric shock.

In my case, I attached my own armoured cable the length of the garden to the wall. (that alternative is that you bury it but it should be 2ft down which is a lot of digging) I went for the fixed to a wall approach and also chose armoured cable as I didn’t want to worry about my kids to driving their bikes and toy cars into it.

Its more expensive for sure, but it is worth the investment for that peace of mind.

What Voltage and Frequency Do I need?

Regarding the frequency and voltage, you have to make sure that you are supplying the right amount of electricity (current) at the right voltage and at the same frequency that your heater and pumps are designed for. For example, in the UK, the voltage is 240V and 50Hz. In the USA, the standard outlet is 110V and 60Hz.

What I am emphasising here is that you cannot take a heater from the UK and plug it into the USA supply and expect it to work. Don’t worry, all the pumps and heaters that we supply are specified for the country in which they will be used!

Also with pumps, the frequency is the rotation rate which again is linked to power. Something that rotates at 50Hz is rotating 20% less than something at 60Hz. So a 50Hz pump will be rotating 20% faster than designed and will overheat on a 60Hz supply – so they need to be designed to run on the correct frequency.

I’m in the USA and being told I need a 240V Supply – is that correct?

Yes, this is correct. To run a Plunge Pool in the USA you are going to need 240V @ 60Hz.

You may see if you Google around pumps and heaters that are rated at 110-120V, 60Hz. To be honest, trying to take a short cut here and not making the right adjustments in your electricity supply is not going to work. Spa Packs (heaters) and pumps that will run on 110-120V are just not powerful enough. At 120V, you will only get something like 1.4KW of power to heat your Plunge Pool which is not enough. Switch that over to 240V and it will now provide you with 5.5KW of power which is more more useful to heating your Plunge Pool.

Don’t Worry, the chances are you already have 240V into your home!

The USA electrical supply is 120V and 60Hz as standard (sometimes is referred to as 110-115V). However, most homes in the USA actually have a split system 120V supply into your homes in the USA. This means that there are two supplies of 120V into your home, again, this is the case in most cases.

DIY Plunge Pool

DIY Plunge Pool

Breaking Ground

This is where the “fun” really begins. You’ve been planning for what seems like an eternity wanted to get started so it is now time to break ground. For me, this was the hard part. As I explained, due to access to my back garden and where I wanted to put the Tub, there was no way that I could actually get a JCB Digger in to help so it had to be done by hand. It was back breaking stuff.

I did however, end up buying a mechanical breaking drill. This made life a lot easier. You can rent them and the ones you rent are even bigger still. The problem that I had was that I was not sure how long it was going to take and I didn’t want to waste money on renting something that was not being used. So I bough a mid range one. It was a god send and made light work of the earth when I did hit the clay and rubble. I would highly recommend one if you are not able to get one of the mini JCBs. The digging took me about two weeks doing a few hours at in the evening and full days at the weekend. There was a lot of rubble and earth to move.

When you are designing how deep you need to go and sticking with your dimensions, make sure that you have allowed for the various layers of type1 hardcore and concrete to a reasonable thickness. The last thing you wan it seats that are too narrow or a Tub that is not deep enough.

As I couldn’t get a digger round the corners of my garden either, I was doing all of this by hand. At this point, my back was hurting and the ground was getting harder so I open for the breaker. This was the best 200 GBP / 200 USD I have spent in ages! Made life so much easier.


The Base

Being a competent DIY’er I had done some electrical work before so that didn’t concern me. The plumbing is “kitchen plumbing on steroids” so I wasn’t too worried about that. What did concern me was whether I could dig a hole and water proof it sufficiently so that it didn’t leak through the walls or through the floor.

My next concern was could I build a structure that was not going to give way under the pressure of the water. I had calculated that it was going to take about 2800 litres which is around 2.8 tonnes of weight – certainly not light. Therefore, I knew I needed concrete and lots of it.

Once I was down to depth (which was a huge milestone for me as my back was killing me and I was fed up of digging) it was time for the type1 gravel to be dropped in. Basically, I put around 6-7cm, or 2” of gravel and then compacted it. You could hire a “wacker” to do this, I just used a heavy piece of timber and a sledge hammer. The whole point of the type 1 is that it can disperse the pressure of the concrete evenly helping it not to crack. Cracks equal leaks so you certainly don’t want these.

After I had put in the type 1, I decided I didn’t want to take any chances so bought a large PVC thick pond liner. This was going to ensure that I didn’t have any leaks. I laid this over the gravel as it was going to take the concrete and hold in the water.

Next were the steel rebars that were held together with metal wire. You see these being used in building structures so I thought it made sense to put them into the build, strengthen the base and stop it cracking under pressure. I’m sure there are some builders out there that would say total overkill, but remember, I was worried about strength and leaks.

Now it was time to mix some concrete.

Mixing the concrete rather than digging a hole was a welcome change. However, what I didn’t realise was just how much concrete I was going to need. I’d looked at hiring a mixer which I would definitely recommend. I did say looked at hiring as I never actually got round to hiring one. The problem I had in my head was I wasn’t sure how long I was going to need it. At this point in my build it was early October so the weather was a bit unpredictable. What I didn’t want to do was hire the mixer and then let it sit unused for a week and have to pay for it. A bit tight? Perhaps! So, I was mixing wheelbarrow after wheelbarrow of concrete. I was mixing sand and cement at around 4 parts sand to 1 part cement. I was also making the mix not too stiff so it would pour ok and be a bit easier to level out. What I also did every step of the way was add lots of water proofing liquid agent. As I said, I wanted to make sure this big hole did not leak. Bit by bit I worked from the bottom up. I filled and had a level base, then it was time for some block work.

Block Work

I hadn’t laid blocks or bricks before but I thought I would give it a go. What I certainly am not going to win any prizes for was speed – I was very slow. Having seen the professionals do it when they were building my extension, I was very slow indeed. That said, it wasn’t a race so it didn’t really matter.

I made the mistake of not getting the base totally square. I was out by about 2cm which isn’t the end of the world but if I had spent a bit more time putting in guide lines, then I think I would have been spot on. The only real tip I have is take you time and check the level of each of the blocks as well as the continuous level of the course of blocks.

I mixed my mortar a little wetter than most as I knew I wanted it to last a bit longer as I was slow. Too wet and your heavy blocks dont sit well so this is something to consider too. If you start with a level base it makes life so much easier. The deepest part of the tub was not 100% level when I started laying the course of blocks. What this means is that you end up having to compensate to try and level things out.

By the time I came to the second layer, I was a bit better. I put in the guide lines and I was also starting on a level base so life was much much easier. When I finished, the top runs were perfectly square.

Mortar Mix

I was mixing the mortar by hand as I wasn’t sure how long it was going to take or how much time I had and because of the time of year, what the weather was going to do. This was back breaking stuff, not as bad as digging the hole, but it was hard work. That said, it was possible to mix in a wheelbarrow and I was mixing at a rate of around 4 to 5 parts sand to 1 part cement. I am sure there are some builders out there that would have a different opinion to this, or perhaps a more refined opinion for the different applications, but this ratio worked for me.

It was not too hard that it didn’t last and set too quickly and it was not too soft and watery either – it was just right. You should be able to pour it if you are backfilling, and make it a little stiffer if you are going to lay blocks with it – just makes life easier.

Don’t make it too hard or too soft as both affect strength of the mix.

What I was also doing with the mortar mix was adding water proofing agent and plenty of it each time. As you can probably guess whilst you are reading this, I was really worried about the Tub leaking! I took every precaution possible to make sure that it was not going to leak.

Build a DIY Plunge Pool

Hardness of blocks

Blocks seemed to come in different hardness offerings. This is for the amount of force they can withstand when you are building tall structures with lots of courses of blocks. Makes sense I guess and I am sure there is a proper explanation out there for what is what. I wasn’t sure exactly what I needed so went with a middle of the road 7N of hardness. Also, I didn’t think that I needed any more because I was only going up a couple of courses so there was not a lot of pressure on them. If anything, the pressure had to be on the sides coming from the water.

How many?

This really depends on how big your project is. My Plunge Pool is 2.3m x 2.6m and I ran two courses on the lower part of the tub and 2.5 courses on the top section (back of the seat) this used roughly 100 blocks in total, I did have a few spare at the end. It’s a simple calculation, take the dimensions of your tub and divide them by the length of the blocks, simple really.

Top tip to make life easier for yourself, pick your dimensions so that you use as many full bricks as you can. The less you need to cut the better. Also, make sure that you order a few more than you need as if you are cutting them they can split. If you drop them, they shatter, so you do need to have some spares on hand.

Cutting them

Having the right tools for the job makes life a lot easier. I bought a block hand saw from Amazon for about 15 quid and it made mincemeat of the blocks when I needed to cut them. It was really easy and you just let the saw do the work. I was even cutting the final half course of block by splitting them into two which with the saw was an easy task. There were more expensive powered cutting disks and saws out there, but for the amount of cuts I was making, I didn’t think it was worth it.

Gunite Holes

Once you have your block walls in place, and they have had a couple of days to set properly, you need to be cutting some holes to slot in the Gunite bodies. These are pretty big holes so you are going to need a core drill bit. As I have said having the right tools for the job make life easier so if you want to really make life easier, go and hire a bore drill and the correct sized core drill bit, probably 2.5” wide. If you want to save yourself a bit of money as I did, then buy yourself a core drill bit online which are relatively inexpensive and use your power drill. This might seem like it is going to be easy but….The first thing is that the core drills do bounce around quite a bit until you have sunken the first 5mm. Getting that first 5mm in the right place is quite hard. So here is what I did. I took one of my spare blocks and measured the height that i wanted the jets to be – roughly in the middle of my back when i was sitting on the seat. Then I cut out a “u” shape with the block saw in the block. This was the right size so that I could then put the core drill bit through. This made life a lot easier when cutting the holes as there was a guide and holding the block in place with my foot, it steadied the core drill for those all important first 5mm. Yes, perhaps hiring a bore drill would have been easier, but I saved a bit of cash with this method.

Once I had all the holes drilled, it was time to drop the gunite bodies into place, and then cement them in. I took a bit of time to make sure that the holes were correctly filled as this is an obvious place for leaks to be. I wasn’t overly concerned as I planned to backfill over the gunite bodies and the pipes anyway. Firstly for strength and secondly for water proofing.

A top tip here is to fit the external pipes into the gunite bodies before you cement into place the bodies themselves. It is quite fiddly to get the pipes into the housings if the bodies are already fixed into place as they were in my case. If I did it again, I would definitely fit all the pipes first, then cement into place the bodies.

It is also important when you put the gunite bodies into place that they are totally perpendicular to the wall of clocks you have laid. If like in my case some of them are not, then your jets do not sit 100% flush onto the walls. Not a huge problem, but it is one of the things I would have taken more time to get right had I known that it was going to be a problem. Not a big issue in my case, but it is something that niggles in my mind as I know they are not 100% even if everyone else doesn’t realise when they use the tub.

Backfill of Concrete

I’d already come to the conclusion that if the block work has nowhere to move, then it cant move! Having not done any block work before, I was a little worried that the structure would collapse under the pressure of 2800 litres of water, especially at the bottom of the tub. Therefore, I made the decision that I was going to backfill all the walls with concrete so it simply was not possible for the blocks to move, regardless of the pressure. Therefore, I dug the gap to be more than I needed and poured cement in behind the walls to more sure they were totally solid. Once my external pipes and gunite bodies were in place and concreted into place, I did the same again. Pouring lots of concrete with large amounts of water proofing agent behind the blocks. In this way, I knew they were going to hold fast because there is nowhere for them to go. It also added as an additional water proofing measure in my mind because I was filling any gaps that there might have been. It was also a good place to get rid of the off cuts of blocks and things so I didn’t need to throw them in a skip, I just used them to strengthen the block work.

As before, If I did this again I would hire a concrete mixer as mixing by hand was a little bit of hard work but doable as I proved.

lower Plunge Pool Plumbing

Tiles, Tiling, Adhesive & Grout

Tiles

I am sure that you would have chosen the tiles that you wanted to use before you broke ground. My recommendations are are quite simple, Go for a tile that is suitable for both walls and floors and wet rooms. Also, make sure that it is ceramic tile rather than a porcelain one. Porcelain is not waterproof. Some of the more knowledgeable of you will also argue that neither are ceramic 100%, but they are as good as waterproof really. There are coatings that you can apply to the tiles if you wish to waterproof them. I didn’t bother and just opted for a ceramic grey tile that was held in place and grouted with grey swimming pool adhesive as detailed below. Again, a year on, touch wood, I have not had any problems with them.

Grout Type

This is important. Don’t just go for a water proof grout, you need to go for a swimming pool grade adhesive and grout. You need to have something that is designed to be submerged under water constantly and not just designed to get wet once a day, eg a shower grout. It is not that much more expensive than the regular wet stuff but the performance is much better. I have not had any problems with mine a year on. It has worn away a little so when I service the tub come spring, I’ll be topping up the grout for sure.

Once you have grouted the tiles and stuck them in place, please remember that you need to leave them to cure for 3 weeks. I didn’t realise this at all. As I mentioned, I was on a mission to finish my tub in time for Christmas and this little nugget of information Brough my schedule forward by 3 weeks!

It is not worth cutting is short. You will have spent so much time and effort on the tub, for a tile to come loose in the first couple fo uses because you were impatient would be awful – I sound like my wife now as that is what she said to me when I wanted to fill the tub after two weeks of waiting!

Edging

Edging is something of a personal preference, so I will describe what I used. Baseically, I used the same kind of edging that you find in a bathroom and that can be bought in a DIY shop. I used plastic edging, but there is no reason that if you are going for a higher quality finish, you couldn’t use a metal edging strip. What I would say, is once it is full and the jets are on, nobody really sees what is underneath so if you want to save a bit of cash, this is for sure an area where you could scrimp a little.

Cutting

Cutting the tiles is something that you should definitely not do by hand. The scoring and breaking method in my opinion is hard work. Spend £20 on a cheap wet diamond cutting machine. This will make your life so much easier. If something doesn’t fit, you can trim it. Just be aware of the chips and bits that fly off during the cutting process. This type of machine doesn’t cut per set it is more of a grind.

Finishing Touches

Fur the purpose of this article, I take the finishing touches to be what is going to surround your tub. In my case, I have a deck and a new fence from Western Red Cedar which finishes off the tub in my opinion perfectly. There are lots of different ways that you can finish things off. They depend on your preference, style and of course, most importantly, budget. Grass, artificial grass, Rocks, pants, decking are all options and again are things you need to think about. I should point out that when I cost out the tub, which came in at just under 5 grand, this does not include the finishing touches.

What you do need to consider is wear and tear and durability. For example, I mentioned that you could put grass around your Plunge Pool. That is fine until your kids invade the tub sending gallons of water splashing everywhere. Chlorine and grand do not mix, certainly in the levels that are in the tub so you need to be mindful that things are going to get wet.

Decking, it gets slippy. There are coatings that you can buy that can reduce this, but I just left it as is and people know that it is going to be slippy. Artificial grass, in my opinion looks rubbish unless you spend a lot of money.

Look, finishing touches are important and something to thing about when you are designing your tub. You don’t necessarily have to have them all worked out, but you are going to need a decent idea of what you need and how you want it to look when you are done. Also, think about the area is going to get wet, it will need to endure the weather as it is outside all year, and it does need to be somewhat practical. Worth spending a few extra quid to make it look the part, especially after the amount of time it will have taken you to create.

Audio Visual

Audio Visual is very much a topic that is close to my heart having spent the last 15+ years in the industry. As you would expect, for my own tub there is a good amount of AV included. Let’s start this section with having a look at the AV I put in place and then we can have a look at what else you could add or potentially do with your build.

Build a DIY Plunge Pool

First things first, I guess you are seeing something of a trend here but planning is key. AV should not be an after-thought and should very much be part of your design. AV is also something that you can adjust to fit your budget. I didn’t spend a fortune on my setup and it suits me just fine – but of course it is possible!

For my setup, I wanted to have a TV so I could watch the Football and the F1 in my tub. Most people would agree that putting a cable box or satellite dish in just for this is a bit of an overkill, so I went with the streaming method for which I already have subscriptions in place; so it was not going to cost me any more.

That said, to put a TV in with Internet you need to make some decisions. Having gone down the wireless route previously and been unsuccessful, I was certain that all my connections were going to be hard wired. For me this was not a huge issue because of the proximity to my office and the network switch that I have in there. That said, I still had to run some considerable lengths of cable. If you are going to run ethernet cable, stump up the extra cash and buy outdoor cable. I didn’t done one of the runs and I have had to run a second cable not even a year on. I either broke down in the elements, or what I think is more likely to be the case, it has been chewed by some fury friends. (get used to these if you live in the countryside as I do. Somewhere dry and warm is obviously going to attract some ‘friends’) In hindsight, I should have gone with a couple of runs of cable as it is easier to fault find in the future – this is the setup I have now after having to re-cable. What I mean with this is that if you are going to need a 20m run of cable, instead of running 20m, run 2 x 10m with a connection half way, somewhere convenient to test connectivity if needed. Once you have your cable run, you will of course need some power.

In terms of power, Try and keep things separate from your main feed into your box. I run a loop of power and a few sockets for things like the AV equipment and the lighting.

Sound. You are probably going to want some speakers. Speakers and audio are a wonderful thing and you can really spend the earth on speakers and waterproof ones. I went somewhat simple and opted for a marine grade amplifier and marine grade speakers. They are a decent size, and the audio is just fine for my requirements. Again, placement. I only went for 2 speakers and they are front facing from the TV unit that I constructed, more on that shortly. However, if I were to do things again, I’d probably opt for 4 speakers adding a couple at the rear of the tub as that happens to be where I sit. It would make for a better audio experience I think. With your audio, you don’t want to be messing around with remote control, they will end up 4ft under after a few drinks! Aim to have a manual adjustable volume control that is easily accessible. Mine is on the side of the TV Cabinet and I have the TV hooked into the marine grade speakers and amplifier. Works great to blast out some tunes from YouTube or watch the Football and F1.

How do you choose an outdoor tv I hear you ask! I will let you into a secret, I didn’t! Nearly a year its still working just fine! Outdoor, IP rated TVs cost a fortune, by a fortune I mean at least a couple of grand. When the aim of the project is to keep the cost down, I wanted to look for an alternative. I looked at some of the pre-made enclosures that are IP rated an again, thought that they were a little bit expensive for what I needed. What I have done is choose the cheapest 32” TV I could find, I didn’t care about the audio which is always the problem with cheap TV’s as I knew it was going to go into my amplifier. I then made a housing to cover it. I didn’t need to make it 100% waterproof, it just needed to be splash proof. I decided that the likelihood of me being in the tub, wanting to watch the football in the driving rain was going to be slim to none. So, the enclosure I made has a sheet of waterproof house wrap under the lid, and a Perspex front to protect the screen from splashing in the tub. I then bought a £15 cover off eBay for an outdoor TV which works a treat. I bought a 55” cover an it drops over the cabinet I made. Perfect!

The cabinet was made from some left overs from the decking, the Perspex was about £20 from the DIY store and I did add some internal fans that can be slid out to stop the front glass misting up with condensation from the hot moist air coming out of the tub – genius! 2 PC fans did the trick with a 12V power supply inside the cabinet. Looks the part!

I did drop an Apple TV into the unit connected to the TV so I can stream from my cell phone or use Apple TV in its entirely too if I wish. The “feed” for the TV comes from a HDMI splitter in my bar and I ran a HDMI cable under the decking to the TV.

Things to consider.

Video, what and from where?
Internet, do you need it and from where?
Power – how much and what needs connecting?
Any external pieces of kit?
How are you going to control it?

With this last point, this is one things that is not ideal with my setup. I can’t change the TV channel from my internet TV account without getting out of the tub and heading over to the computer in the bar that drives it. Not the end of the world, but a waterproof wireless keyboard would be an ideal solution – not sure if they exist, not looked!

My cabinet is permanently outside, under the cover which happens to match the colour of my Plunge Pool cover – so it looks quite nice. A confederation would be a mechanism to raise and lower it (that would be very cool)

Filling and Testing

This for me was probably the most nerve racking and exciting time of the build. Was it going to stay together. Was it going to leak like mad. Was it going to fall apart as soon as a bit of water was in there. Was the filer and pump actually going to work and produce enough bubbles so it at least looked like a Plunge Pool. Was it going to heat up to temperature?

Filling the Plunge Pool

I had so many questions going on in my head it was untrue. Nevertheless, it was a super exciting moment to turn on the hose pipe and let it start to fill.

I had calculated that the filling process was going to take best part of 3 hours given that the average hosepipe under normal pressure allows 1000 litres of water an hour to flow. The first part went well and filled up the footwell quite quickly, the water didn’t seem to be escaping so all was good.

I had to wait about another 90 minutes for the water to come up over the seats and again, so far so good. The big test was when the water hit the jets and started to fill the piping, was it going to leak? It didnt.

The next big test was when the water reached the skimmer, it would flow down, through the piping into the pump and the would be ready to be tested. Earlier in the article I explained my woes of power outages so I will not recount the story again here. That said, to test the system, I started the pump on low speed and let it rang for a good 5 minutes.

I was checking all around the Control Room for leaks as that was where most of the joints are and also where some of the more difficult joints were. As I suspected, I had a bit of a drip on the joint that was not 100% square as I did not leave enough room. If that was it, then I was laughing.

I turned the pump onto full and water started spraying everywhere. No problem, just needed a bit of a turn on the screen joints on the top of the pump. Awesome, we had good movement. I turned on the blower and voila! It looked like a Plunge Pool, although at this stage, it was about 8 degrees and a very cold tub. Now it was time to turn on the heater and see if we could heat this body of water up to temperature.

It was quite cold outside as it was December so I knew that this was going to be a slow precess. I left it a couple fo hours, went to check and I had moved up a couple degrees. Great I though, this will heat up in no time. Of course, this was not the case.

The heating of water is not a straight line, not is the cooling which we’ll come onto later. For the first 5 or so hours I was heating the water at about a degree an hour, but that soon dropped and I now know that the working time of the heater in cool weather (it was a bit quicker in the summer, more like 1 degree an hour) is 0.5 degrees Celsius an hour. That is fine, it means that you can’t decide an hour before you want to use the tub and it does need a bit of planning, but it is certainly manageable.

Some 40 hours later after I had started the process, I did hit the desired 39 degrees Celsius – I’d done it. I’d built a Plunge Pool, that didn’t leak much (we’ll look at this int he next section) that heated up and looked the part.

You’ll understand the sense of satisfaction this creates when you have designed and built you own.

Repairing any Leaks

Af first, I thought that having to top up the tub up once a week was normal and it was just evaporating. This is not right, you should not have to top it up that often at all. If your water level is dropping, you have a leak.

I had a leak, well, actually I had a couple. The first leak that I had was a constant small leak that came from the bottom of a T join that linked the inlets to the skimmer before they went into the pump feed.

I tried drying it and then using some of the pipe cement, but that was not enough. What I need up having to use was plumbers wet putty which is designed to stop leaks on wet and dry pipes. A chemical reaction allows the putty to set even when things are wet. I went through a couple of tubes of this stuff to get it right but it worked.

The second leak that I had was for the Ozone. I mentioned that I removed the Ozonator from the system as it wasn’t working, but there were too many weak joints. Anything that is held together with a jubilee clip in a high pressure system like a Plunge Pool is going to leak, and this is what happening. Under high pressure, eg when the jets were on full, the joint were leaking water at a rate of knots.

I decided to lock off the system, drain the excess water from the Ozonator section of the pipework and cut it out. I replaced it was regular water pipe and two 90 degree elbows. Job done, no leaks.

A year on, I probably top up the tub every couple of months and this is because of evaporation and when people are going in and out all the time, the water level does drop, but nothing drastic. It also only takes 10mins to bring it back up to the correct level (middle of the skimmer) with the hose pipe.

Chemicals & Maintenance

Why do we need Chemicals in a Plunge Pool?

We need chemicals in a Plunge Pool primarily to kill bacteria that could breed in a warm damp environment. By using a combination of chemicals we are able to remove the bacteria which could be harmful to us from our Plunge Pools and control the water for longer.

What Chemicals do I need for my Plunge Pool?

When we are talking about Plunge Pool chemicals, we are really talking about 6 things

  • Sanitiser
  • pH Increaser
  • pH Decreaser
  • Total Alkalinity Increaser
  • Anti Foam
  • Clarifier (optional)

Let’s have a look at what each of them does.

Sanitiser

Sanitiser is the main chemical that is going to kill bacteria in your Plunge Pool. There are two main choices here. You can either opt for Bromine or you can choose Chlorine. I am going to write an article at some point about the difference and pros and cons between the two, but for this article, I am going to concentrate on Chlorine as that is what I use in my own tub and it is more popular.

Just as a side note, Bromine is particularly good if you have sensitive skin or react to Chlorine. It means you can still enjoy the Plunge Pool without the associated skin complaints!

Bromine is a sanitizer, oxidizer, and algicide that is used in swimming pools and Plunge Pools. In its original state, bromine is a reddish brown liquid, but for pools, it can be found in tablet, granular, stick, and liquid sanitation products (though you would never use pure elemental bromine in a pool or spa). Any liquid bromine products that you may find are diluted with water and other chemicals for safe handling and better performance.

“Bromine” isn’t true bromine, but the name is used to describe any chemical that releases hypobromous acid into the water. This takes place in two ways:

  • The two-part system consists of sodium bromine activated by an oxidizer and is typically used in smaller volumes of water (spas).
  • The solid, dissolvable form of bromine (tablets, granules, etc.) is formed when bromine is bound to an organic molecule.

What are the Pros and Cons of Chlorine?

A chlorine purification system is the standard method of sanitizing your pool water. Chlorine is added directly to the water to kill bacteria, viruses, and algae. Using chlorine purification system requires the pool owner to test the PH of the water, measure out the correct balance of chemicals, and add them to the water. This system is done routinely by the pool owner as part of their routine pool maintenance.

Chlorine Pros

  • Chlorine is a powerful oxidizing agent thereby getting rid of a lot of bacteria in water.
  • Chlorine is commercially available
  • Chlorine is very economical

Chlorine Cons

  • Chlorine does not exterminate all bacteria. Complex microorganisms are known to become dormant in the presence of chlorine but not exactly killed
  • Chlorine is not green. It is harmful to the environment.
  • Commercially available chlorine (Hypo) disintegrates into Chlorine gas rapidly when exposed
  • Super-chlorination poses danger to humans over a period of time
  • Downstream water treatment systems like Resins, RO/UF membranes may be damaged by excessive chlorine at inlet.