Hot Tub Lights: The Ultimate Guide to Lighting a DIY Hot Tub

Last updated: September 2026

You lift the cover on your DIY hot tub. The steam hits your face, the water is crystal clear, and the colours slowly fade from red to green to blue to white. Ah, bliss. Lighting sets the scene more than anything else in a hot tub, so it’s worth getting right, and it’s far easier to get right before the walls are rendered than after.

This guide covers choosing, powering, controlling and fitting a light in a block, concrete or ICF hot tub or plunge pool, like the one in my DIY in-ground hot tub build guide.

Why choosing a hot tub light is harder than it should be

Choosing a light should be simple. When it came to my build, it wasn’t. It was confusing, and what connected to what just wasn’t clear. Search for hot tub lights and you mostly find small LEDs made for plastic shell tubs. They weren’t going to be much use in my block hot tub.

So I looked at swimming pool lights, and that seemed to be the answer. It did come with what I affectionately started calling the “swimming pool tax”. Anything pool related came at a cost. The colour-changing pool light I liked cost around £230/$300, and when I asked about powering it, the supplier tried to sell me the £350/$400 power supply designed for it. Knowing a reasonable amount about electronics, I found something else to power it for around £20/$30. It worked, but it wasn’t clear and it wasn’t cheap.

That’s what led me to launch my own light, which I’ll come to below. First, the things to look for in any light.

LED or halogen?

This one’s easy. Halogen is a thing of the past. LED is as bright or brighter, lasts far longer, costs a lot less to run and needs a much cheaper power supply. Buy LED.

Look for:

• An IP68 rating, which means it’s made to be permanently underwater.
• Low voltage: 12V AC or 12V DC is typical for pool lights.
• RGBW rather than RGB. A dedicated white LED gives a clean white. RGB-only lights mix a white that often looks bluish.
• Surface mount or niche? Traditional pool lights sit in a niche set into the wall. Surface-mount lights screw to the wall, which is much easier in a DIY tub.

How bright, how big and how many?

There are two broad types:

• Larger pool lights light up the whole tub from one position.
• Spot lights are smaller and throw a sharper cone of light from the wall. You use several of them.

There’s no “better” option. It depends on the look you want. What matters is total wattage. As a rule of thumb from my own lights, about 35W of LED will light a hot tub up to roughly 3m x 3m (10ft x 10ft), and a single light of 25W or more will usually do a typical tub. Below that, you’ll want more than one. Manufacturers measure brightness differently, so treat this as a guide rather than a rule. It’s always better to have a little too much, because you can dim it or choose softer colours, but you’re stuck if you find it’s too dim once the tiles are on.

Size matters too. When I got samples in, one LED light was so big it could have been mistaken for a UFO, a hangover from the halogen days. Many pool lights stick out 30–40mm (1.2–1.6in) from the wall. In a hot tub, where feet and backs are close to the walls, thinner is better.

Tub or pool	Rough guide from the 35W rule of thumb
Small tub, up to about 2m x 2m (7ft x 7ft)	One 35W light, or two to four 6W spots for a softer look
Typical tub, up to about 3m x 3m (10ft x 10ft)	One 35W light
Plunge or cocktail pool	Two 35W lights, or a row of 6W spots spaced evenly along the long side

Where to put the light

This is the bit people most often overlook. Don’t point the light at where you’ll be sitting. Imagine building a beautiful tub and then having a light shining in your eyes every time you lean back.

• A single larger light usually goes low down, either on the bottom step (where mine is) or on a side wall. On a side wall, pick one you’re not facing as you walk down the steps.
• Spot lights sit near the surface for the effect they create, typically 100–150mm (4–6in) below the waterline and no more than about 200–250mm (8–10in). Space them evenly.
• Keep it away from the jets and any seat where it will be under someone’s back or feet.

A thin, surface-mounted light gives you far more freedom here, because it doesn’t need a niche and takes up almost no space.

How to power a hot tub light

After my “swimming pool tax” experience, here’s what I learnt. The light needs a low-voltage supply of the right type (AC or DC) and big enough for the light’s current. It doesn’t need to be a special pool-branded unit, as long as it’s a good-quality supply mounted somewhere dry and ventilated, such as your control room. My lights run on a 12V DC supply, and it’s included in the box.

Two things catch people out:

• Voltage drop on long runs. At 12V, a long thin cable loses a noticeable chunk of voltage. As an example, 10m (33ft) of 1.5mm² cable each way carrying 3A drops around 0.7V, about 6%. Keep the power supply close to the tub and use a heavier cable for long runs.
• Mains in the wrong place. Only low-voltage cable should go anywhere near the water. The mains side of the power supply is a job for your electrician.

Safety rules: UK and USA

In the UK, the IET’s guidance on outdoor hot tubs applies the swimming pool rules in BS 7671 Section 702. Lights in or next to the water should be SELV at no more than 12V AC or 30V ripple-free DC, with the supply outside the zones around the tub. Switchgear and junction boxes shouldn’t be installed in the zones next to the water, with SELV junction boxes the exception. In the USA, NEC Article 680 covers underwater lights, so check with your inspector. There’s more in Hot tub wiring explained and A guide to hot tub electrics.

Can I connect my light to the spa pack?

Not directly. The light socket on a spa pack is designed for the small LEDs in shell tubs. Balboa’s BP packs give 10V AC at 2A maximum, and Gecko’s in.ye gives 12V DC at 1.3A. A proper pool light draws much more, and my 35W light draws up to 3A at 12V DC.

I found this out the hard way. I plugged a swimming pool light into my pack and started going through £300/$350 circuit boards. After the second one went, I did some serious investigating, because it was costing me a fortune. The light was simply drawing far more current than the board could handle.

For years my answer was to keep the light completely separate, on its own switch. That still works fine. But there’s now a better way. My Hot Tub Light Connection Kit is a relay that takes the pack’s light signal (drawing just 40mA) and switches the light’s own 12V DC supply. So the light button on your topside turns the pool light on and off, and your board stays safe. I’ve explained how it works, which packs it suits, and why you shouldn’t connect it to an ACC pack, in Can I control a swimming pool light with a hot tub spa pack?

How to control the light

Mine was on a simple switch for years. It’s on a slow fade between colours, and to be honest, once you’ve found a setting you like, you’ll probably leave it there.

My lights come with a remote to change the colour and mode. The remote isn’t waterproof, so keep it in its holder by the control room or indoors, not on the side of the tub. With the connection kit fitted, you switch the light on and off from the topside and use the remote only when you want a change.

How to install a hot tub light, step by step

Every light has its own instructions, so follow them. The principles are the same for most surface-mount lights.

1. Choose the position before you build

Mark the light position on your plans with the seats and jets. You need to know where the cable goes before the blockwork or ICF goes up.

2. Build in a sleeve

Set a length of spare pipe into the wall or step behind where the light will go. The size doesn’t matter much, as long as the cable and a coil of spare fit inside. This does two jobs. It gives the cable a protected route through the wall, and it stores a loop of spare cable behind the light, so you can lift the light to the surface later without draining the tub.

3. Take the sleeve up above the waterline

Run the sleeve or conduit so it rises above the waterline before it heads to the control room. Water will sit in the sleeve up to the level in the tub, but gravity stops it going any higher. This means you don’t need to seal the cable into the wall, and you can pull a new cable through later if you ever need to. I went for a permanent cable on my own build, which means I’m stuck if the cable ever fails. I’d take the sleeve route today.

4. Keep joints out of the water

Run the light’s own cable up the sleeve and make any joint or extension above the waterline, ideally in the control room. Never join cables in the water or inside a part of the sleeve that’s flooded.

5. Surface-mount the light

Once the tiles are on, drill the fixing holes, fit wall plugs and screw the light to the wall or step. With a sleeve behind it, the spare cable tucks in neatly and the light sits almost flush.

6. Wire and test in the control room

Connect the power supply and, if you’re using it, the connection kit, following the wiring diagram supplied. Test the light before you fill. Then test it again with water in.

The Super Slim light

This is why I launched my own light. I wanted something good enough, different enough, and easy enough to fit and set up, without the swimming pool tax.

• 35W RGBW LED, with dedicated white LEDs as well as red, green and blue.
• 230mm (9in) across and only 8mm (0.3in) thin. As far as I know, it’s the thinnest surface-mount underwater LED on the market.
• IP68 and resin filled, so it’s made to live underwater.
• 12V DC, 3A. The power supply and the spa pack connection kit are included, along with the remote.
• Surface mounted, with no niche, on a wall or a step.

You can get the Super Slim DIY Hot Tub / Swimming Pool Light from my shop, and in the UK from parts4tubs.co.uk.

For smaller tubs, or for lighting a plunge pool with several spots, there’s the Super Slim 6W spot light. It’s 110mm (4.25in) across and 8mm thin, in 316L stainless steel, and comes with its own power supply and remote. It’s also available as a 4 pack or a 6 pack. If you want to switch the spots from your topside, check with me through the shop before you order.

Common mistakes

• Plugging a pool light straight into the spa pack’s light socket.
• Pointing the light at the main seat or lounger.
• Forgetting the cable route until after the walls are rendered.
• Joining cables below the waterline, or sealing a cable permanently into the wall with no way to replace it.
• Mounting the power supply somewhere damp or unventilated.
• Running 12V a long way on thin cable, then wondering why the light looks dim.
• Leaving the remote on the side of the tub.

Planning your own build?

Lights are easy when they’re on the drawing before the first block goes down. My DIY hot tub plans include the plumbing layout and a full parts list, and The Ultimate Hot Tub Control Room Guide shows where the power supply, pack and everything else go. If you’re building something custom, like a plunge pool with a row of spots, I can draw it up as architectural CAD with a 3D plumbing design.

Still working out the rest of the build? Start with I want to build a hot tub: where do I start? and the DIY hot tub shopping list. If you’re adding a water feature too, see adding a water feature to your DIY hot tub.

FAQs

How many lights does a hot tub need?

For a typical tub up to about 3m x 3m (10ft x 10ft), one 35W LED is usually enough. With smaller 6W spot lights, you’ll need several, spaced evenly.

What voltage should a hot tub light be?

Low voltage. In the UK, lights in the water should be SELV at no more than 12V AC or 30V DC. Most pool lights run on 12V AC or 12V DC. Check what your light needs and use the right supply.

Can I plug a pool light into my spa pack?

Not directly. Spa pack light outputs are designed for small shell-tub LEDs. Use a separate switch, or a relay such as the connection kit, so the pack only switches the light’s own supply.

Where should I put the light in a hot tub?

On the bottom step or a side wall, facing away from where people sit. Spot lights go nearer the surface, around 100–150mm (4–6in) below the waterline.

Can I replace a hot tub light without draining the tub?

With a surface-mount light and a sleeve holding spare cable, yes. You can unscrew it and lift it to the surface. That’s why the sleeve is worth building in.

Got a question about lighting your own tub? Drop it in the comments below. I read them all.

Cheers,
Andi

You can also find me on my socials;

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 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