Adding a Water Feature to a DIY Hot Tub: Pumps, Flow and Solenoid Valves

Last updated: September 2026

The sound of flowing water is naturally relaxing. A fountain, waterfall or small stream can seriously level up a hot tub setup. It adds a touch of luxury and creates a calming atmosphere for you, your family and your guests. Here’s how to design and install a water feature for a DIY hot tub, including how to switch it on and off with a solenoid valve.

Types of water feature

There are many types. Ideally you plan them into the design from the start, because retrofitting can be challenging, time-consuming and expensive. Think beyond looks: it should blend with the rest of your backyard, but you also need to consider installation, flow rates and maintenance. The main types are:

• Waterfalls (including water blades: see wide arc water blade installation tips).
• Fountains.
• Streams.

They all give a soothing sound and can even make a gentle cooling mist on a warm day. Fountains can be made from acrylic, stainless steel, natural stone or custom-built sculpture, each with its own style from sleek and modern to rustic. If you want a whole edge to spill over instead, take a look at adding a spill-over hot tub and how to build a DIY infinity or overflow hot tub.

Materials

Pay close attention to materials, because hot tub water contains chlorine, bromine or other sanitisers that not every material can handle. A fountain made for a garden pond may look right, but it isn’t necessarily rated for hot tubs or pools. If the material isn’t compatible it can corrode, break down or discolour, ruining the feature and even contaminating your water. Always check the manufacturer’s specification and make sure it’s rated for your chemicals. See the guide to balancing hot tub chemicals.

DIY builds only

This post is about DIY builders crafting a custom tub. If you have a pre-made plastic shell hot tub, I’d strongly advise against modifying it for a water feature. The structure isn’t designed for that.

Size, space and position

• Size and space: waterfalls and fountains often look smaller in pictures than in real life. Measure twice, plan once.
• Position: will it sit at the end of a rectangular tub, be part of a wall, or rise from the middle of a round tub? Position affects the flow and the splash pattern, so be strategic. Splash also means water loss, so check where it lands.

Flow rates

Waterfall flow rates are measured in gallons per minute (GPM) or gallons per hour (GPH), and this is where things get tricky. The feature mustn’t overpower your system. If it’s low-flow, you’re probably fine. If it pumps out more than about 1,000 GPH (roughly 17 GPM, or 63 litres a minute), it’s time for pump maths.

• What’s the maximum flow rate of your pump?
• How many jets will run alongside the waterfall?
• Do the jets and the water feature added together stay within the pump’s capacity?

Each component needs the pressure it requires without sacrificing the others. For a sheet or blade, a thin sheet needs around 5 GPM per foot of width, but check the manufacturer’s figure. There’s a full explanation in how to size a pool overflow or spillover.

Flow control

There are two parts to control: the flow, and the feature itself.

For flow, the most common and effective method is a ball valve, also called a waterfall regulator. It lets you tweak the flow until it looks right. If the pressure is too high, use an inlet reducer: smaller pipe means less water. If your waterfall ends up shooting a wild horizontal blast across the yard, it’s time to tone it down.

Independent pumping (highly recommended)

Whenever possible, give the water feature its own pump. Then:

• You can turn it on and off independently.
• You don’t compromise the flow to the jets, which are essential for a good soak.
• It’s simpler to maintain and control.

Where do you connect a water feature in the plumbing?

In short, you don’t. Put the water feature on its own pump with its own inward suction, so it can’t affect the jet flow or the circulation and filtration. The plumbing is simple, and looks something like this.

For the wider picture, read how hot tub plumbing works and DIY hot tub plumbing. Keeping pool and hot tub water systems apart is covered in why pool and hot tub plumbing should remain separate.

How do you turn a water feature on and off?

Decide how you’ll control it at the design stage. If your hot tub has a waterfall, you probably only want it running while you’re in the tub, otherwise it would empty the tub onto the cover. With its own pump, you simply switch the pump. If it’s part of a larger feature and you want to control elements individually, you can use a manual stop valve or ball valve. But if you want to switch parts on and off electrically, use a solenoid valve.

What is a solenoid valve?

A solenoid valve is an electronic valve that opens and closes with an electric current. You can’t turn it by hand, so it’s useful if you want the feature to run automatically or at set times: connect it to a timer. There are two types:

• Normally closed (NC): closed with no power, open when powered. This is the best choice if you want the feature off by default, such as a waterfall that only runs while you’re in the tub.
• Normally open (NO): open with no power, closed when powered. Ideal if the feature runs most of the day and you only stop it occasionally.

What to look for when buying one

• Voltage: they come in 12V, 24V, 110V, 240V and so on. Match your power setup. Low voltage is a sensible choice near water.
• Pipe size: match the diameter of the pipe to your feature. Most DIY builds use 1.5in pipe, and adapters let you convert sizes.
• Timer integration: connect it to a timer or a smart control for hands-off operation.
• Chemical resistance: check the body and seals suit pool water.

How to install a solenoid valve

Install it after any check valves and pressure relief valves. A solenoid is either fully open or fully closed: there’s no half-flow, so plan for that. There’s a flow arrow on the body, so align it with the flow direction, because getting it wrong causes pressure and flow problems.

Say you’re installing a 240V 1in solenoid valve, labelled A in the diagram:

1. Start with a 1in socket to male thread adapter (B), which reduces your 1.5in pipework to 1in.
2. Connect a short piece of 1in pipe (C).
3. Use a 1in to 1.5in reducing bush (D), which fits inside a 1.5in socket (E).
4. Note the direction of the flow arrow on the valve (A). In this example it runs left to right.

The left side (inlet) is plumbed to the water supply, usually coming off the jet lines, and the right side (outlet) goes to the water feature. If you can add a manual ball valve downstream as a backup, do.

Wiring it up

This valve is normally closed, so it stays shut until power is applied. Wire it to your supply with a simple inline switch on the live conductor. Switch on and the valve opens, so water flows. Switch off or lose power and the valve closes. That’s a simple, reliable arrangement, and you don’t need complex automation unless you want it. Any mains wiring should be done by a qualified electrician and protected by an RCD (GFCI in the USA). See hot tub wiring explained and hot tub electrics.

Common mistakes

• Connecting the feature to the jet plumbing and starving the jets.
• Buying a garden fountain not rated for pool chemicals.
• Underestimating the size in real life.
• Forgetting a way to switch it off, then finding the tub level dropping.
• Mixing up the flow direction on a solenoid valve.

Designing a tub with a water feature?

It’s much easier to plan the feature into the design than to add it later. My DIY hot tub plans give you a full plumbing layout to build on, and for a tub with a waterfall or a fully custom layout, I can produce an architectural CAD and 3D plumbing design. Try the free Tub & Pool Designer Pro to lay it out first.

FAQs

Can I add a water feature to my hot tub?

On a DIY tub, yes, and it’s best planned in from the start. I wouldn’t modify a pre-made plastic shell tub for it.

Should a water feature have its own pump?

I strongly recommend it. It lets you switch the feature independently and stops it stealing flow from the jets.

How do I control the flow of a waterfall?

Use a ball valve, which is often called a waterfall regulator, and reduce the pipe size at the inlet if the pressure is too high.

What is a solenoid valve used for?

It lets you switch a water feature on and off electrically or with a timer. A normally closed type stays shut when there’s no power.

Are garden pond fountains safe in a hot tub?

Not necessarily. Materials must be rated for hot tub or pool chemicals or they can corrode and discolour.

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

Cheers,
Andi

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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