How to Install a Counter Current Swim Jet in a Plunge Pool, Swim Spa or Hot Tub

Last updated: September 2026

Most of us don’t have room in the back garden (or backyard) for a 25m pool. A counter current swim jet gets round that. It pushes a current of water at you, you swim against it, and you stay in the same spot. Fit one to a plunge pool, cocktail pool or DIY swim spa and you can swim for as long as your lungs allow. In my case that isn’t very long, but that’s a me problem, not a swim jet problem.

Commercial systems can run to many thousands of dollars. The swim jets I supply are pump-driven units designed for DIY builds, and this post shows you how to position, install, plumb and wire one.

What is a counter current swim jet?

A swim jet (also called a counter current unit or endless pool jet) is a machine that makes a flow of water for you to swim against. When you swim at the same pace as the current, you stay put, so you can swim “endlessly” in a pool only a few metres long.

That’s what makes it such a good fit for a DIY plunge pool, cocktail pool or swim spa. You get a pool to cool off and lounge in most of the time, and a workout when you want one. If you’re still deciding what to build, have a look at How to build a DIY exercise pool and Swim jet considerations: everything you need to know before you commit to a size.

Who is this swim jet for?

There are systems on the market that cost four to six times the price of this one. They’re very much for the pro swimmer. This swim jet is not for the pro swimmer. It’s good enough for a fitness swimmer, even a good swimmer, but not an athlete in training.

The difference comes down to how the current is made:

	Pump-driven (electric) jet	Hydraulic system
How it works	A pump draws water in through the unit and pushes it back out through the nozzle	A hydraulic power pack drives a propeller in the pool wall
Current	Good for fitness swimming, adjustable	Stronger and wider, suited to training speeds
Cost	Far lower	Several times more
Best for	Most DIY plunge pools and swim spas	Serious swimmers and triathletes

You can adjust the flow and the angle of the jet. If you want a stronger current but don’t want to pay hydraulic prices, the dual pump version runs the same jet from two pumps.

How does the swim jet work?

The swim jet is a self-contained unit. Water is drawn in through the sides of the unit and delivered back into the pool under pressure from the jet pump. The design inside the unit is there to keep the bubbles down, so you get a current rather than a jacuzzi.

On the front of the unit there are air buttons: one turns the pump on and off, one turns the LED light on and off, and an air control lets you adjust the flow. The button isn’t electrical. Pressing it pushes a pulse of air down a thin tube to an air switch in the control box, well away from the water, and that switches the pump. It’s clever, simple, and it keeps mains electricity away from the person in the pool. More on that in the wiring section.

The four swim jet options

All four use the same swim jet. What changes is how much of the plumbing and pumping comes with it. Prices are as listed in my shop at the time of writing.

Option	What’s included	Best for
Swim jet (faceplate, body and tubes only), $997	The swim jet body and faceplate, parts 1–19 on the parts diagram, including the 1W 12V LED light, air buttons and hoses	You’re sourcing your own pump, air switches and plumbing
Swim jet (no pump), $1,597	The swim jet, plus 2 air switches, 2 x 75mm couplers, 2 x 75mm to 2in reducers, 2 x 2in ball valves, and 2in 45° and 90° bends	You already have a suitable pump
Swim jet with pump, $1,997	As above, plus 2 x 2in unions and a 4HP single-speed pump (230V)	Most DIY plunge pools and swim spas
Swim jet with dual pump, $2,699	The swim jet, 2 air switches, 4 x 75mm couplers, 4 x 75mm to 2in reducers, 4 x 2in ball valves, 8 x 2in 90° bends, 2 x 2in unions, 2 x 2in tees and 2 x 4HP single-speed pumps (230V)	Stronger swimmers who want more current

The same unit works in gunite or shotcrete, poured concrete, block, ICF, fibreglass and liner pools. The LED light needs a 12V power supply, and that isn’t included. More on that below.

The parts breakdown

The installation steps below refer to these part numbers, so keep this list handy. The same list and diagrams are in the swim jet installation manual (PDF).

Before you start: size and position

Pool length

The pool or tub should be at least 4m (about 14ft) long. Any shorter and the current hits the back wall and comes back at you as a wave, which is really off-putting when you’re swimming. Longer is better.

That’s why I say “hot tub or plunge pool” with a caveat. A typical 7–8ft hot tub is too short for a swim jet. You need a swim spa or plunge pool sized tub, and my swim spa plans and 14ft x 7ft plunge pool plans start at that length for exactly this reason. If you’re hoping to swim in an existing hot tub, read Can I use my hot tub as a swimming pool? first.

Depth

The centre of the swim jet nozzle should be 250mm (10in) below the water surface. This is the same whatever construction method you use. Your skimmer sets the water level, so work the jet height out from the skimmer, not from the top of the wall.

Dimensions

The body of the swim jet (part 15) is 260mm (10.24in) in diameter. In a block or concrete wall, leave an 11in (about 280mm) hole so there’s room to concrete around it and seal it.

Where it goes

• Put it in the middle of an end wall, so you swim straight down the length of the pool.
• Keep steps, benches and baja ledges out of the swim lane.
• Think about the view. You’ll be facing the jet every time you swim.
• Plan the control room at the same time. The pump has to sit below the waterline, so the control room needs to be low enough. See Hot tub control room design considerations.

Installing in a concrete, block, ICF, gunite or shotcrete pool

On a solid wall, the rubber gaskets and clamp ring (part 14) aren’t needed. Set them aside.

1. Set the height. Mark the finished water level, then set the jet so the nozzle centre ends up 250mm (10in) below it.
2. Set the body flush with the finished surface. This is the key step. The front of the jet body (part 15) must line up with what will be the finished surface of the pool, after render, waterproofing and tiles, not the bare blockwork. It’s exactly the same principle as setting a jet body. See How to install gunite jet bodies.
3. Fix it in. On a block or ICF build, leave the 11in hole, fit the body, and concrete around it so it’s held firmly. On gunite or shotcrete, fix it to the steel so it can’t move when the concrete is sprayed.
4. Waterproof around it. The joint between the jet body and the wall is a classic leak point. Take your pool-rated membrane carefully up to and around the body, following the manufacturer’s detailing for penetrations. My waterproofing, grout and tile adhesive guide covers the products.
5. Finish the surface with tiles or pool paint.
6. Fit the faceplate (see below).

Installing in a liner pool

The steps are the same up to the point where the liner goes in. The body (part 15) is fixed so it sits flush with the finished wall, right up behind the liner. Then:

1. Cut or spike the 16 screw holes through the liner.
2. Place a rubber gasket (part 14) on each side of the liner.
3. Screw the plastic clamp (compression) ring in place with the 16 screws. Tighten evenly, working across the ring, so the liner is squeezed into a tight seal all the way round.
4. Only cut out the liner inside the ring once it’s clamped.
5. Fit the faceplate as below.

Thinking about a liner for your build? I’ve covered the pros and cons in Can I use a liner on my DIY hot tub?

Fitting the faceplate (all pool types)

1. Connect the air tubes to the buttons. Remove the screw nut from the top of the pump button (part 1) and the light button (part 3). Slide the nut onto the air tube first, push the tube on, then tighten the nut back down.
2. Protect the air lines. Slide the protective pipe covers down the air tubes to where they meet the buttons.
3. Thread everything out through the conduit. Feed the LED light cable and both air tubes out through the back of the jet body and into the conduit (part 16). Attach the conduit to the body and tighten the cable gland (part 17).
4. Keep the conduit and exhaust hose above the waterline. The final position of the conduit (part 16) and the exhaust hose (part 18) must be above the water level, as shown in the final installation diagram below. If they’re below it, water finds its way in.
5. Fit the support frame. Slide the support frame (part 8) firmly into the body and screw it in with the four M6 stainless screws (part 12).
6. Fit the lid. Place the faceplate (part 6) over the support frame and fix it with the four M5 screws (part 5).

Plumbing the pump

The jet connects with 75mm fittings, which reduce to 2in for the pump. On the kits, that’s what the couplers and reducers are for. A few rules:

• The pump must be installed below the waterline. This is stated on the product pages, and it’s not optional. Below the waterline, the pump stays flooded and primed. Above it, it can lose prime and run dry. If your control room ends up higher than planned, read Using a priming circuit above ground on a centrifugal pump, but it’s much better to design it right.
• Keep the swim jet on its own circuit. The jet pump draws from and returns to the jet. It doesn’t go through your filter or heater, which are sized for circulation, not a 4HP pump.
• Fit ball valves and unions either side of the pump, so you can take it out for service without draining the pool. See Hot tub pump union sizes explained.
• Keep runs short with sweeping bends. Every metre of pipe and every tight elbow costs you current.
• Make every joint properly. Prime and solvent weld each joint, and pressure test before anything is buried or concreted. My PVC solvent weld guide shows how.
• Watch 2in vs 50mm. In the UK, imperial 2in pipe and metric 50mm pipe look almost the same but aren’t. Pick one system and stick to it.

On the dual pump kit, the two pumps are teed together so they feed the same jet.

Wiring and the air switch control box

Here’s why air buttons matter. The UK wiring regulations treat a pool as a special location. In the zones nearest the water, no switches or accessories are allowed at all, and the IET recommends treating outdoor hot tubs the same way (IET Wiring Matters). An air button has no electricity in it. You press it, a pulse of air travels down the tube to the air switch in the control box, and the air switch does the switching.

Latching vs momentary switches

Latching switches turn on when you press them and stay on until you press them again, like a light switch at home. Momentary switches are only on while you hold them down, like a doorbell or an electric drill.

A swim jet needs a latching air switch: press once to start the pump, press again to stop it. If you’re sourcing your own air switches for the jet-only version, make sure they’re latching and rated for your pump. I go into more detail in Hot tub air switches: the ultimate guide and How to change an air button and latching relay.

The supply

The pump is 230V. Follow the wiring diagram for the control box, and have a qualified electrician install the supply:

• UK: a dedicated circuit with 30mA RCD protection (Type A as a minimum, or whatever the maker specifies), armoured cable for the outdoor run, and a local isolator outside the zone around the water. The IET suggests 2m from the edge. A new pool or hot tub circuit is notifiable under Part P.
• USA: a 240V circuit (not 120V) with GFCI protection and a disconnect within sight, following NEC Article 680 as your area adopts it. Most areas want a permit and an inspection, including the bonding.

A 4HP pump is a big load. Your electrician should size the cable and breaker from the pump’s rating plate, and allow for everything else on the pool (circulation pump, heater or heat pump). There’s much more in Hot tub wiring explained.

The LED light

The light in the faceplate is 1W at 12V, and it needs a 12V power supply, which isn’t included. Use a proper safety isolating (SELV) transformer, installed where the regulations allow, not in the zone next to the water. The light button on the faceplate switches it through its own air switch.

Testing

1. Pressure test the pipework before it’s buried or concreted in.
2. Fill the pool to its normal level, with the water halfway up the skimmer mouth.
3. Open both valves and check the unions for drips.
4. Only then run the pump. If you’re just checking the electrics before the pool is full, don’t run it for more than a second or so. Pumps aren’t designed to run dry, and a dry run can wreck the seal.
5. Check the buttons start and stop the pump and the light, and try the air adjuster.
6. Swim it. Adjust the nozzle angle until the current feels straight down the middle.

Common mistakes

• A pool that’s too short. Under 4m (14ft) and you’ll be swimming in your own wave.
• Setting the body flush with the blockwork instead of the finished surface. By the time render, membrane and tiles go on, it’s recessed.
• Measuring depth from the wall top rather than the finished water level.
• A control room above the waterline, so the pump won’t stay primed.
• Running the conduit or exhaust hose below the waterline.
• Plumbing the jet through the filter and heater.
• No valves or unions, so servicing the pump means draining the pool.
• Buying momentary air switches for the jet-only kit.

Troubleshooting

Problem	Things to check
Button does nothing	Air tube pushed fully on and nut tight at both ends, tube not kinked or split, isolator and RCD/GFCI on
Pump starts then stops straight away	Momentary switch fitted instead of latching, or a faulty air switch
Weak current	Valves not fully open, air adjuster setting, air leak on the suction side, long runs or tight bends, pump not primed
Lots of bubbles or surging	Water level too low, air getting into the suction pipework or pump lid
RCD or GFCI trips	Don’t keep resetting it. Get the pump and connections checked. See Hot tub breaker tripping? 5 troubleshooting tips

Safety

A 4HP pump pulls a lot of water. Keep the faceplate and all its screws fitted whenever the pump can run, and never let anyone play with their hair or fingers near the intakes. In the USA, the Virginia Graeme Baker Act requires anti-entrapment drain covers on public pools and spas after a child was trapped by a hot tub drain (Pool Safely). It doesn’t apply to your back garden, but I’d follow the same thinking on the rest of your pool plumbing too: certified covers and two main drains. See Installing a main drain.

Want to see one going in on a real build? Follow this infinity hot tub with a swim jet in Virginia and Darren’s swim spa in Arizona.

Planning your own swim spa or plunge pool?

The swim jet is the easy bit to add if the pool is designed around it from the start: the right length, the jet at the right height, and a control room low enough for the pump. My swim spa plans and plunge pool plans give you the CAD drawings, plumbing layout, parts list and video course.

If your space is an odd shape, design it in the free Tub & Pool Designer Pro software, and I can turn it into architectural CAD and a 3D plumbing design, swim jet included.

When you’re ready for the jet itself, pick the jet only, jet with plumbing (no pump), jet with pump or jet with dual pump.

FAQs

How long does a pool need to be for a swim jet?

At least 4m (about 14ft). Shorter than that, the current bounces off the back wall and makes waves.

How deep should a swim jet be installed?

The centre of the nozzle should be 250mm (10in) below the water surface, whatever the wall construction.

Can I add a swim jet to a hot tub?

Only if the tub is swim spa sized, at least 4m (14ft) long. A standard 7–8ft hot tub is too short to swim in.

Can I fit a swim jet to a liner pool?

Yes. The same unit comes with rubber gaskets and a clamp ring that seal it to the liner with 16 screws.

Does the swim jet pump go through the filter and heater?

No. It runs on its own pump and plumbing. Your filtration and heating stay on a separate circulation system.

Is a pump-driven swim jet strong enough?

For fitness swimming, yes. If you’re training seriously, a hydraulic system gives a stronger current, at several times the price. The dual pump version is the middle ground.

Got a question about fitting a swim jet to your 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