Can You Build a DIY Infinity Pool? Balance Tanks, Plumbing and Design

Last updated: September 2026

An infinity pool is the dream: water spilling over the edge so the whole pool seems to float into the view. It’s also the pool most people assume is too expensive and too complicated to build themselves. It’s not simple, but with careful planning and some elbow grease I’ve helped a client build their own infinity pool in the backyard without breaking the bank. Here’s how to plan yours and the mistakes to avoid.

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Design considerations

1. Location. The location decides the view. Ideally you want an uninterrupted, panoramic outlook. Putting the pool on a rise adds to the view from the pool and gives you space to build around.
2. Size and shape. This depends on your space and taste. Think about how much room you want for the surrounding deck or patio too.
3. Structural design. An infinity pool is more complex than a normal pool. It needs a basin to catch and recycle the water spilling over the edge, and the structure must take the weight of the water and the force of the spill. Consult a qualified professional about the structure. For more on wall types, see hot tub wall construction options.
4. Materials. Concrete, fibreglass and vinyl are all used. Choose for your region and climate.
5. Plumbing and electrics. They differ from a standard pool: think about circulation and filtration, and how you’ll get power to the pool and surroundings. Electrics must be installed by a licensed electrician.

Get the base right at the start and you won’t be spending a fortune on repairs later. See how to build a concrete slab or base and DIY concrete plunge pool for the groundwork.

Plumbing considerations

1. Circulation. A domestic pool is usually turned over every 6 to 8 hours. Calculate the flow you need from your pool’s volume. Note that the flow going over the edge is often much higher than the flow needed for turnover, so it’s worth designing how these two work together.
2. The infinity edge system. Water spilling over the edge must be caught in a trough and returned to the balance tank, then pumped back through the filter and heater to the pool.
3. Edge flow. Plan about 5 GPM per foot of edge (about 60 litres per minute per metre), with a perfectly level, sharp weir. A 20ft (6m) edge needs roughly 100 GPM (about 380 litres a minute). Rounded or uneven edges need more, and thicker sheets need a lot more. The maths is in how to size a pool overflow or spillover.
4. Suction. Use twin main drains with VGB-compliant covers to protect against entrapment and to keep the pump fed if one is blocked. See installing a main drain.
5. Equipment location. Put the pumps, filter and heater somewhere accessible, ideally below the water level in a screened equipment room. My control room design guide explains the principles, and the control room post has more.
6. Energy efficiency. Choose efficient pumps (variable speed helps) and consider solar or a heat pump to keep running costs down. Pool electricity costs matter.

What is a balance tank?

The balance tank is a separate tank that holds the water level steady in the main pool so the water flows smoothly over the edge. The overflow drains into the catch trough, then into the balance tank. From the tank, the water is pumped through the filter and heater and back into the pool.

It has three jobs. It holds the water bathers push out when they get in, it holds the water in transit over the edge and in the trough and pipework (which all drains back when the pump stops), and it provides a reserve so the pump never sucks air. That’s why the tank has to be sized with care: when everyone gets in, the tank must have room for the surge.

How big should the balance tank be?

Size it for what actually ends up in it, rather than as a multiple of the flow. Add up:

• Displacement. Each adult displaces about 70 litres (about 15 US gallons). Ten people is around 700 litres. For a pool, builders often size the surge for a rise of about 2in (50mm) across the whole water surface. On a 20ft x 10ft (6m x 3m) pool, that’s about 250 US gallons (roughly 950 litres).
• Water in transit over the edge, in the trough and in the pipes, which drains back when the pump stops.
• An operating reserve so the pump always has water above its suction.

Physical space matters too. The tank needs to be easy to reach for maintenance. Balance tank sizing is a place to get an engineer or a designer to check your figures. I go through worked examples in how to build a DIY infinity or overflow hot tub, and design points in infinity pool design considerations.

Materials you’ll need

1. Concrete for the shell and surrounding structures, thanks to its durability and shape flexibility.
2. Rebar in a grid to reinforce the shell. See rebar.
3. Waterproofing: a liquid or sheet membrane over the shell, and don’t forget the trough. See waterproofing, grout and tile adhesive.
4. Tile or finish for looks and to protect the shell. See hot tub tiles.
5. Plumbing components: pumps, filters, skimmers if you have them, pipework, drains.
6. Catch basin or trough in concrete or another durable material, plus the balance tank.
7. Electrical components such as lights and pumps, fitted by a licensed electrician to local code.

Common mistakes

• Out-of-level weir, so all the water runs over one low spot.
• An undersized balance tank that overflows or starves the pump.
• A single suction point.
• No structural engineer involved.
• Skimping on waterproofing around the trough.

Real builds to look at

For inspiration and detail, see Etienne’s infinity hot tub project, an infinity hot tub with a swim jet in Virginia and DIY infinity hot tub. For related pool types, read building DIY plunge pools, DIY lap pool and adding a spill-over hot tub.

Can I help with your infinity project?

Yes. My infinity hot tub plans show an overflow edge that acts as the balance tank (sizes are hot tub scale, from 6ft to 12ft square, with CAD drawings, plumbing diagrams and video lessons). For a full-size infinity pool or something custom, I can produce architectural CAD and 3D plumbing design, and you can lay out your idea first in the free Tub & Pool Designer Pro software. Get in touch with your vision and we’ll see how to make it real.

FAQs

Can you build an infinity pool yourself?

Yes, though it’s more complex than a standard pool. The structure and the balance tank need careful design, so involve a structural engineer and get the plumbing sized properly.

What is a balance tank in an infinity pool?

It’s a tank that catches the water spilling over the edge, holds the surge from bathers and provides a reserve for the pump, then feeds the pump, filter and heater.

How much flow does an infinity edge need?

About 5 GPM per foot of edge (60 litres per minute per metre) for a thin sheet over a perfectly level sharp weir, more for thicker sheets.

How often should a domestic pool be turned over?

Typically every 6 to 8 hours, but the edge flow is often higher than the turnover flow, so design both together.

Do I need twin drains?

Yes. Twin main drains with VGB-compliant covers are the safe design and keep the pump fed if one is blocked.

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