Can You Build a DIY Swim Spa? How to Choose a Swim Jet

Last updated: September 2026

Can you build a DIY swim spa? It’s one of the questions I’m asked most often, and the short answer is yes. Swim spa, endless pool, counter current and swim jet tend to get mixed and matched to describe a small pool with a machine that lets you swim continuously. For this article, a swim spa is a small pool with a machine at one end that lets you swim against an artificially generated current.

I won’t go deep on building the pool itself. I have plenty on that in how to build a DIY cocktail pool or spool and on my YouTube channel. What I want to focus on is the swim jet: how it works, the options, and how to choose the right one.

What is not a swim jet?

Before the definition, here’s what a swim jet isn’t. It’s not a strong swimming pool return, and it’s not a strong hot tub jet or even a cluster of hot tub jets. Swim jets have had real research and engineering put into them, so they work for anyone from enthusiast swimmers to Olympians. That’s why we’re not talking about the cost of a few hot tub jets here. If you follow me you know I don’t take the shortcut: it’s the real thing or nothing.

What is a swim jet?

A swim jet creates a counter-current in a pool so you can swim continuously in place. There are two main types:

1. Electric (pump-driven) swim jets. These use an electric pump, an impeller, specially designed jets and a suction system. The pump generates the flow that makes the current.
2. Hydraulic swim jets. These use hydraulic pressure to create the current, so there are no electrical components at the poolside, which many people consider safer. The pressure is transmitted through lines to make the flow.

Both work well. The choice comes down to your preferences on safety, installation and maintenance.

How do I choose a swim jet system?

1. Power of the jet

Think about how fast you want to swim and how much resistance you need. Are you more of a Homer Simpson or a Michael Phelps?

• Casual swimmers looking for light exercise can manage with a less powerful system.
• Serious swimmers, or anyone after an intense workout, need a more powerful unit with higher flow rates.

Flow is measured in gallons per minute (GPM). As a rough guide I look for a system delivering at least around 600 GPM for a worthwhile swim, though check what the maker actually specifies. More power usually means more cost, so don’t overspend on a Michael Phelps system you don’t need.

2. Noise

Nothing ruins a swim like a loud machine. Noise varies between systems, so compare decibel ratings, and if you can, test one or ask the manufacturer. Hydraulic systems tend to be quieter than electric ones.

3. Bubbles in the stream

A key difference between a proper swim jet and a hot tub jet is bubbles. Bubbles mean air is mixed into the stream, which gives less effective resistance, uses more energy and can make it hard to see while you swim. Choose a bubble-free system that pushes only water, and ask the manufacturer to confirm.

Built-in or retrofit?

If you’re building a new pool, design the swim jet in from the start. Choose the model, get its dimensions, and build it into the pool wall. The units are self-contained, so it’s a bit like incorporating a square box into the wall. It’s straightforward.

Retrofit units suit an existing pool where you want swim spa functionality, and they tend to be cheaper. But I wouldn’t recommend one in a new build: it’s an off-the-shelf solution that won’t give you the finish of a built-in unit.

How much do swim jets cost?

I hate generalised questions like this, because it’s like comparing a Toyota with a Ferrari. It depends on your setup and the type of jet. What I can say is that a swim jet is a big-ticket item. Adding one to a cocktail or plunge pool can add a large share to the overall build cost, and more again if you’re a strong swimmer who needs a higher specification. Price up the jet first, then the pool around it. To see a size of pool that fits, look at what a swim spa costs and mini pool ideas.

A more cost-effective swim jet for DIYers

If you want a practical alternative to the very expensive systems, I designed a swim jet for DIYers. It’s simple to install and ideal if you’re building your own swim spa. See how to install a counter-current swim jet for the install.

Key features of my swim jet

1. Compact design. It fits into the wall of your swim spa during construction. The pump should ideally sit directly behind the jet for maximum flow. If it’s 10 to 20 feet away, you risk losing a lot of flow.
2. Maximum flow. It’s designed for the highest flow rate I could get, for a good swimming experience.
3. Easy installation. The housing is concreted into the wall during the build. Once the final surface is finished, the faceplate goes on for a clean look. On the shop page the nozzle should sit about 250mm (10in) below the water surface, and the pool should be at least 4m (14ft) long.
4. Pump options. It’s available with or without a pump. The package with a pump includes a 4HP single-speed pump (230V). If you supply your own, remember that standard swimming pool pumps have lower flow rates, so you’ll need a much larger one. Check the flow, not just the horsepower.

The full range is in the shop, including the swim jet with pump. My guide to swim jet considerations goes deeper on pool size, depth and compatibility.

Building the pool around it

Once you’ve picked the jet, you need the pool. A swim spa is essentially a plunge or cocktail pool with a jet in it. My swim spa plans give you the drawings, plumbing and a shopping list for that, and I have guides on DIY plunge pools, DIY exercise pools, what is a spool? and using a hot tub as a swimming pool. For anything custom, use the free design software and I can turn it into architectural CAD and 3D plumbing.

In conclusion

You can build a DIY swim spa with a counter-current to swim against. Research the models on the market and choose one that matches your swimming level. A swim jet also adds to the appeal of a pool, and any good realtor will tell you the same. But they aren’t cheap. They’re not just big jets, and a lot of engineering has gone into creating a real swimming experience.

FAQs

Can you build a DIY swim spa?

Yes. You build a small pool, usually around 4m (14ft) or longer, and fit a swim jet in one wall. Design the jet in from the start.

How big does a DIY swim spa need to be?

About 4m (13 to 14ft) long at least, otherwise the current bounces off the far wall and disrupts your swim. It also needs to be deep enough that your hands don’t touch the floor.

Electric or hydraulic swim jet: which is best?

Electric jets are the more common choice and suit recreational swimmers. Hydraulic units are stronger and quieter with no electrics at the poolside, but they’re pricier.

Why do bubbles matter in a swim jet?

Bubbles mean air is mixed in, which reduces the resistance and the efficiency of the current and can make it harder to see. A bubble-free stream is better.

Can I use my own pump with a swim jet?

Yes, but pick one with enough flow. Standard pool pumps have lower flow rates, so you may need a much larger pump than you’d expect.

Got a question about your own build? 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