Mini Pool Ideas: Small Backyard Pools You Can Build Yourself

Last updated: September 2026

Want somewhere to cool off in the garden or backyard without giving the whole lot over to a full-size swimming pool? A mini pool might be exactly what you’re after. They fit into small spaces, cost a fraction of a big pool to build and run, and if you heat one, you can use it for much of the year.

This blog and my YouTube channel are all about building things yourself, so that’s where I’ll focus. There are plenty of mini pools you can buy off the shelf, and I’ll touch on those too, but mostly this is a 1,000ft overview of the ideas, the construction options and what goes into building your own. Where a topic needs more detail, I’ll point you to the full guide.

What is a mini pool?

A mini pool is simply a small pool built for relaxing, cooling off and socialising rather than swimming lengths. There’s no official definition, and you’ll hear lots of names for much the same thing. Here’s how I’d separate them:

Type	Typical size and depth	Best for
Plunge pool	3–6m (10–20ft) long, 1.2–1.5m (4–5ft) deep	Cooling off and standing up in, plus swimming on the spot with a swim jet
Dipping pool	Often at the small end of a plunge pool	A quick dip on a hot day, or a cold dip after a sauna or hot tub
Cocktail pool or spool	3–5m (10–16ft) long, 1.1–1.4m (3½–4½ft) deep, with benches	Sitting and chatting with a drink. Add heat and jets and it’s a spool.
Cold plunge	Usually one person, around 1–1.2m (3–4ft) deep	Short cold immersions, often next to a hot tub
Stock tank pool	A galvanised farm water tank, usually only about 2ft (60cm) deep	A cheap, quick summer splash pool

What they all have in common is less water. That means less to filter, less to heat and fewer chemicals than a full-size pool. It doesn’t mean less care, though. A small body of water gets dirty and out of balance faster than a big one, so it still needs a proper filtration and sanitising system.

If you’re torn between a mini pool and a hot tub, read Hot tub vs plunge pool: which should you build?

Mini pool ideas

A few ideas that work really well in small spaces:

• A plunge pool with a swim jet. If your pool is at least 4m (14ft) long, a counter current swim jet lets you swim on the spot. See how to build a DIY exercise pool.
• A cocktail pool with a bench and an in-water lounger. Perfect if you’ll mostly be sitting in it with friends. My cocktail pool and spool guide covers the full build, and how to build a concrete lounger covers the lounger.
• A heated spool. Warm in winter, cool in summer. See What is a spool?
• A hot tub and mini pool side by side. A soak, then a dip. My hot tub pool combo guide explains how to plan the two together.
• A cold plunge. See how to build a DIY cold plunge pool.
• A semi-raised pool with a wall at seat height. Less digging, and the wall doubles as seating. The walls have to resist the full water pressure with nothing behind them, though, so they need proper reinforcement.
• A stock tank pool. The budget option. See how to build a DIY stock tank hot tub, which covers the same filtration and heating kit.

How much does a mini pool cost?

Professionally installed, not cheap. In the USA, Angi puts the average plunge pool at about $28,000, with most people paying $10,000–$40,000. Vinyl runs $10,000–$30,000, fibreglass $18,000–$55,000 and concrete $20,000–$75,000. In the UK, Checkatrade puts a concrete in-ground plunge pool at £15,000–£25,000 plus labour, and a fibreglass one at £7,500–£16,000.

Building it yourself is a fraction of that, but I won’t give you one figure, because it depends so much on size, finishes, heating and how much you hire in. Price up your own parts list before you start.

What construction methods are there?

Method	Good	Not so good	DIY-friendly?
ICF (insulated concrete form)	Strong, insulated, light to handle, easy to route pipes through	Blocks cost more than plain block	Yes, my first choice
Core-filled concrete block	Cheap, familiar, available everywhere	Poor insulation, heavy, slow if you’re new to it	Yes
Poured concrete	Very strong, any shape	Needs formwork strong enough to take the pour	Possible, with help
Fibreglass shell	Fast install, smooth finish	Fixed sizes, delivery and crane access, often more expensive	Groundwork only
Block or steel wall with a vinyl liner	Cheaper finish upfront	Custom liner, tricky to fit, needs replacing	Partly
Portable (inflatable or frame)	Cheap, set up in an afternoon	Short lifespan, basic filtration	It’s not really a build

A few thoughts on each:

• Concrete, block and ICF are what I’d build. In its most basic form, you dig a hole, pour a reinforced slab, build the walls, then plumb, waterproof and tile it. I’m oversimplifying, but that’s the principle. I’d pick ICF, which I describe as Lego for adults. See block, ICF or poured concrete? and the best ICF blocks.
• Gunite and shotcrete are sprayed concrete. They’re brilliant for curves, but it’s a specialist trade with specialist kit. See alternatives to gunite and shotcrete.
• Vinyl liners have to be custom made for your pool, and fitting one can be problematic. You may end up paying a pool professional to install it, which kind of defeats the whole DIY thing. More in Can I use a liner?
• Portable pools are the quickest and cheapest option. I’m not a fan, given this blog is about building pools, but they have their place for a summer or two.

Whichever method you choose, a mini pool holds several tonnes of water. A 12ft x 8ft pool, 4ft deep, holds around 11,000 litres (2,900 US gallons), or about 11 tonnes. So it needs a reinforced slab, rebar tied into the walls, a hydrostatic relief valve, a pool-rated waterproofing membrane and a flood test before you tile. My DIY plunge pool guide walks through the whole structure, and rebar explained and why you need a hydrostatic relief valve fill in the detail.

How do you build a small pool? The steps

1. Plan and check permissions. Decide the size, depth, steps, benches, plumbing routes, control room and power supply. Check for buried services (LinesearchbeforeUdig in the UK, 811 in the USA) and whether you need a permit.
2. Dig. The hole needs to be deeper than the water, to allow for the sub-base, slab, render, membrane and tiles.
3. Base. Compacted sub-base, a membrane, main drains and hydrostatic relief valve, a rebar grid and a ready-mix concrete slab.
4. Walls, steps and benches in ICF or core-filled block, with the returns, skimmer and any jets set in as you go.
5. Plumbing back to the control room. Pressure test it before you backfill.
6. Waterproof with render and a pool-rated membrane, then flood test.
7. Tile with pool-grade adhesive and grout, and let it cure properly.
8. Electrics by a qualified electrician.
9. Surround: coping, paving or decking, and a safety barrier.
10. Fill, balance the water and commission.

What does the plumbing look like?

The plumbing on a mini pool is relatively simple, but it has to be right. Again, this is the 1,000ft view:

• Pump and filter. The pump pulls water from the pool, pushes it through the filter to remove debris, and returns it clean. A pool without jets only needs a small circulation pump. A variable-speed pump costs more upfront but much less to run. For how often the water should pass through the filter, Fluidra quotes the UK guidance of a 4–8 hour turnover for domestic pools.
• Skimmer. It draws water from the surface, catching leaves and floating debris in a basket before they sink. It also sets your water level. See how to install a skimmer.
• Main drains and returns. Water is drawn from the bottom through the main drains and pushed back through the return inlets, which keeps the whole pool circulating. Use two main drains at least 3ft (1m) apart with anti-entrapment covers. In the USA, the Virginia Graeme Baker Act requires drain covers that meet ANSI/APSP/ICC-16. See installing a main drain.
• Sanitiser. You need something to keep the water clear and healthy. Chlorine is the most common, whether dosed by hand, from a floater or feeder, or made from salt with a salt chlorinator. UV-C can reduce how much you need, but it doesn’t replace a residual sanitiser.
• Heater. If you want to use it outside the summer, add heat. An air source heat pump is the sensible choice for a pool this size. The US Department of Energy puts pool heat pumps at a COP of 3 to 7, which means several kW of heat for each kW of electricity. A small 3kW spa heater on its own is far too slow. See how to choose the right air source heat pump and heater size for your pool or hot tub.

If you’re not familiar with plumbing, this is where I can help. My plunge pool / cocktail pool plans include plumbing layouts for both hot-tub-style and traditional pool setups (details below).

Design features to consider

• Size. How much space do you have, and how many people do you want in it? Remember the surround too: paving or decking, somewhere for loungers, and the control room.
• Shape. Mini pools can be any shape you like, but building curves is much harder than squares and rectangles, both in the blockwork and in the tiling. Blocks and ICF are square for a reason.
• Depth. Around 1.2–1.4m (4ft–4ft 6in) suits most adults for standing and cooling off. Shallower is better for young children and benches. No mini pool is deep enough to dive into. The American Academy of Orthopaedic Surgeons’ warning is simple: “One shallow dive can wreck a neck”. Put up a no-diving sign.
• Steps and benches. Built-in steps make getting in and out safer. A bench turns a plunge pool into a cocktail pool. See the ultimate guide to steps.
• Lighting. An underwater light lets you use the pool at night and looks fantastic. Lights in the water must run at extra-low voltage (12V). See the ultimate guide to hot tub and pool lights and my super slim DIY pool light.
• Water features. A waterfall, water blade or fountain adds sound and interest. Give it its own pump. See adding a water feature.
• Decking or paving. Pick something non-slip that suits the garden. See deck ideas.
• A cover. It keeps debris out, cuts evaporation and holds the heat in. The DOE says a pool cover can cut heating costs by 50–70%.

Safety barriers and fencing

A mini pool is small, but it’s still deep enough to drown in, and small children are drawn to water.

• USA: Most jurisdictions require a barrier. The CPSC’s safety barrier guidelines call for a barrier at least 48in high, with no gap a 4in sphere can pass through and self-closing, self-latching gates that open away from the pool. Some areas require 60in. Local codes set the actual rules, so check with your building department.
• UK: There’s no law requiring a fence around a private pool, but RLSS UK recommends secure fencing at least 4ft high. I’d add a lockable cover too.
• Everywhere: non-slip surfaces around the edge, a handrail on the steps, and an adult watching whenever children are in or near the water.

My plunge pool guide has a full UK vs USA barrier comparison. For permits, see Do I need a permit for my hot tub? In England, the Planning Portal says an outdoor pool often doesn’t need planning permission, with exceptions for listed buildings, conservation areas and other designated land.

Keeping a mini pool clean

Small pools go green quickly if you ignore them. A simple routine keeps them right:

• Test the water regularly and keep it in range. The US CDC recommends at least 1ppm free chlorine in pools (2ppm if you use stabiliser) and at least 3ppm in hot tubs, with pH 7.0–7.8, tested at least twice a day when in use. If you run your mini pool hot, treat it like a hot tub. My chemical levels guide has the full ranges.
• Skim, brush and vacuum. Net off leaves before they sink, brush the walls and steps to stop algae getting a hold, and vacuum the floor.
• Look after the filter. Clean a cartridge or backwash a sand filter as the manufacturer recommends. See sand filters explained.
• Run the pump long enough for a full turnover every day.
• Shock when needed, for example after a busy day or a lot of rain.
• Cover it when it’s not in use.
• Shower before you get in. Suncream and body oils are a big load on a small pool.
• Top up automatically if you can. See auto top-up systems.

Common mini pool mistakes

• Treating it like a big bucket rather than a pool: no rebar, no hydrostatic relief valve, a single main drain.
• Relying on waterproofing additives instead of a proper pool membrane, or tiling before a flood test.
• Choosing a curved shape that’s beyond your blockwork or tiling skills.
• Undersizing the heater, or not planning a cover.
• No room to work in the control room, and no drain in it.
• No barrier or lockable cover.

Planning your own mini pool?

If a standard size fits your space, my plunge pool / cocktail pool plans give you architectural drawings, plumbing layouts, steps and lounger details, a build guide and videos, in imperial and metric. They come in seven sizes, from 10ft x 7ft, 12ft x 8ft and 14ft x 7ft up to 20ft x 10ft.

Want to swim in it? Add a counter current swim jet to a pool of 14ft (4m) or longer. If your space is an odd shape, sketch it in the free Tub & Pool Designer Pro software, and I can turn it into architectural CAD and a 3D plumbing design. For a mini pool and hot tub together, there’s the hot tub and pool combo design consultancy.

FAQs

What is the smallest size for a pool?

There’s no minimum, but for a pool you can stand and move around in, around 3m x 2m (10ft x 7ft) and 1.2m (4ft) deep is a practical starting point. Anything smaller starts to feel like a cold plunge or a hot tub.

How deep should a mini pool be?

Around 1.2–1.4m (4ft–4ft 6in) for standing, or 1.1–1.2m (3½–4ft) if it’s mainly for sitting on benches. It will never be deep enough for diving.

Can I build a mini pool myself?

Yes, if you’re a reasonably confident DIYer and you plan properly. ICF or core-filled block on a reinforced slab is very achievable. Leave the electrics to a qualified electrician.

Do I need a fence around a small pool?

In most of the USA, yes: typically a 48in barrier with a self-closing, self-latching gate. In the UK it isn’t a legal requirement for a private pool, but RLSS UK recommends secure fencing at least 4ft high.

Can I heat a mini pool?

Yes. An air source heat pump plus a good cover is the best combination for most people. A small spa heater on its own is too slow for this much water.

Got a small space and a big idea? Tell me about 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