Brian’s DIY Infinity Hot Tub in the Bahamas: From Concept to Reality

Last updated: September 2026

A DIY infinity hot tub was what Brian wanted when he got in touch with me back in April 2022. Most clients come to me because they don’t want to pay the eye-watering prices that spa and pool builders charge. Brian had a different problem.

Where he wanted to build his infinity hot tub, at his new home under construction in the Bahamas, there simply were no pool or spa builders. So Brian wanted his existing contractors to do the work. The catch was that they had never built one before. That’s exactly what I do, so I was more than happy to start talking with Brian about how I could help him and the team.

Where it started

To get things started, Brian sent me a picture of a load of sand and the view he wanted to frame with the hot tub. This was going to be one amazing tub when it was finished. It just needed a little bit of vision to get it going.

The concept

I drew up a concept for Brian, and as I do with all my custom clients, we went back and forth with the design until he was happy. Brian knew what he wanted, so it didn’t take long to get the concept done. If you’re curious how that works, I’ve explained the custom design process step by step.

As with all projects, turning that concept into reality is always the challenge.

With the design complete, it was over to the guys to start clearing the area. I’m not going to post pictures of piles of sand, but like any DIY hot tub, this infinity tub needed a proper base. To lay it, they had to get down to rock so they weren’t building on sand. From there, they built up to the right level. There’s more on this stage in my concrete slab and base guide.

Brian and the team opted for poured concrete in forms. This was the same method they had used for the walls of his new home, so they knew what they were doing. This time was a little different, because they needed to get the plumbing into the walls first, which is exactly what they did.

Forming up the walls

When you’re forming up a hot tub or an infinity hot tub, you generally pour in sections. A couple of times I’ve had clients do what’s called a mono-pour, where you pour the whole thing in one go, but that’s not the norm. It’s a lot more difficult, so the concrete crew needs experience of doing it. If you’re mixing by hand in a small mixer, you won’t be doing a mono-pour. I compare the options in block, ICF or poured concrete?

The team poured the base, then the outer walls, and then it was on to the inner seating. For the seats, they filled the void with crushed rock and aggregate. That’s a good idea, because it’s a lot cheaper than filling it with concrete. Concrete isn’t the cheapest of materials, so reducing the volume puts some of those dollars back in your pocket.

Forms off

Here you can see what the infinity hot tub looked like once the forms had been removed. It was taking shape nicely.

Waterproofing and tiling

With the walls in place and cured, they were ready for the next stage: sealing and waterproofing.

The waterproofing layer is the important bit. Depending on where you are, there are different brands. In the USA, I like Hydro Ban from Laticrete. In Europe, Ardex S 7 Plus is a great material. They’re not cheap, but in my opinion they’re the best for the job. I used to suggest a PVA wash to seal the surface before the membrane, but I wouldn’t now: the membrane makers want it applied to clean render or concrete, with no sealer or primer unless their own data sheet asks for one. I explain why in my guide to waterproofing, tile adhesive and grout.

Once there are a couple of coats of the waterproofing layer on, the tiles go on, and you can start to see what the final “product” is going to look like. See hot tub tiles for choosing them.

The control room and balance tank

While the tiles were being done, the team turned their attention to the control room.

Brian has a huge veranda deck looking out to sea, and underneath is a storage area they used for the control room. It’s out of the elements and below the water line, so it’s a perfect location. There’s more on why that matters in hot tub control room position.

Because this is an infinity hot tub, it needs a balance tank for the overflow. When an infinity tub is full, the water sits right up to the lip of the overflow edge. There also needs to be a store of water that can be pumped back to the tub to keep it overflowing when nobody is in it.

That’s the job of the balance tank: to store water and let the pump return it to the tub. For example, if two adults get into the tub, they each displace around 70 litres (about 18 US gallons) of water, and that water needs to go somewhere. When they get out, it’s returned to the hot tub so it overflows again. It’s quite a straightforward process when you think about it. The balance tank just needs to be sized properly, and I go through the calculation in how to build a DIY infinity or overflow hot tub.

Brian’s balance tank is in the control room. The overflow water is caught in a trough and fed by gravity back into the balance tank. We put an auto top-up in there, and an overflow too, because the Bahamas can get a lot of rainfall. Without an overflow, heavy rain would fill the tub and then the balance tank.

Brian’s control room also has an automatic salt dosing system and UV for added clarity. Brian’s goal was as little maintenance on the tub as possible. If you’re weighing that up, see saltwater hot tub pros and cons.

The finished tub

With the tiles in place and cured, it was time to fill the tub. Brian had the water delivered so it filled quicker. There were, of course, the usual leaks you get on a first fill. That’s totally normal and happens to everyone.

Simply WOW! How good does this look?

Teething problems

I’d love to say that DIY hot tubs, infinity or not, always go to plan with no problems. Quite the contrary: there are always teething issues.

Brian had some pretty large air locks after filling his tub, which we needed to clear. If that happens to you, see how to clear a hot tub air lock.

He also had water draining back into the balance tank when the pumps weren’t running. That’s because the equipment is below the water line and the team forgot to put a Hartford loop in the hot water returns. So the water drains back into the balance tank and then out of the overflow.

A good quality one-way (check) valve from Jandy, Hayward or Pentair (a swimming pool part) will fix this. But in the Bahamas, you can’t just pop down to the local pool store and pick one up. Brian did try to retrofit a Hartford loop, but it’s just too low, and the water still drains back. For now, he keeps his circulation running 24/7 as a temporary measure.

Thank you, Brian

Brian, thank you for all the pictures and video. It’s been a total pleasure working with you on this project, and I’ve thoroughly enjoyed it.

If this has got you thinking about an overflow edge of your own, have a read of infinity and zero edge design considerations, and take a look at Etienne’s build in Etienne’s infinity hot tub project and Doug’s in infinity hot tub with swim jet in Virginia.

Planning your own infinity hot tub?

My infinity hot tub CAD plans come in a range of sizes and include the CAD drawings, the plumbing for the overflow edge and balance tank, a parts list and the video course. If, like Brian, you want something designed around your own site and view, my custom hot tub design consultancy gets you a design and my support through the build, or I can turn your own layout into architectural CAD and a 3D plumbing design.

FAQs

What is a balance tank on an infinity hot tub?

A tank, usually in the control room, that catches the water flowing over the edge and stores the water displaced by bathers. The pump draws from it and returns the water to the tub, so the edge keeps flowing whether the tub is empty or full of people.

Why does water drain back into the balance tank when the pumps stop?

If the equipment sits below the water line, water can siphon back through the return lines. A Hartford loop in the returns or a good check valve stops it, and it’s much easier to design in than to retrofit, as Brian found.

Can a general contractor build an infinity hot tub?

Yes, if they have a proper design to work from. Brian’s team had never built one, but they knew concrete. See hiring a contractor to build your hot tub.

Got a question about an infinity build like Brian’s? Drop it in the comments below. I read them all.

Cheers,
Andi

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Thanks - Andi

 

Hi, Andi here. I own Buildahottub.com 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.

Fast forward to 2025, I've helped over 1400+ 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