How Much Does a Garden Pond Cost to Build in the UK?

A garden pond is one of the most wildlife-friendly features you can add to your garden. Even a small pond attracts frogs, dragonflies, newts, and birds. Larger ponds with filtration and planting become dramatic focal points. Costs range from under £200 for a simple DIY wildlife pond to £30,000+ for a koi pond with professional filtration.

Average Garden Pond Costs

Pond Type	DIY Cost	Professional Installation
Small wildlife pond (2-3m2)	£150 – £400	£500 – £1,500
Medium ornamental pond (5-10m2)	£500 – £1,500	£2,000 – £6,000
Large formal pond (10m2+)	£1,500 – £4,000	£5,000 – £20,000
Koi pond (specialist)	£3,000 – £10,000	£8,000 – £30,000+

What Affects Garden Pond Costs?

Size and Depth

Size and depth are the primary cost drivers. Larger ponds need more liner, more excavation, more rock and planting, and larger or multiple pumps and filters. Wildlife ponds should have a shallow area (less than 30cm) for amphibians and at least one area 60-90cm deep for overwintering. Koi ponds need a minimum 1.5m depth to protect fish from predators and temperature extremes.

Liner vs Concrete

Flexible liner (EPDM rubber): The most popular material for garden ponds. 45mm EPDM liner costs £3 – £8 per m2 (supply only) and has a 50+ year lifespan. Allow 60cm extra length and width to overlap the pond edges. Easy to install yourself for simple shapes.

Pre-formed rigid liners: Available in fixed shapes up to about 1,000 litres. Easy to install; limited to set sizes and shapes. Cost £50 – £300 for the shell.

Concrete: Expensive to install (professional work) but extremely durable for koi ponds and formal water features. Can be built in any shape. Requires sealing with a pond-safe render and regular crack monitoring.

GRP (fibreglass): Used for koi ponds and formal builds. Hard-wearing, smooth (good for koi), and custom-made. Expensive.

Filtration Systems

A wildlife pond with native planting can be self-regulating with no mechanical filtration. A koi pond or heavily stocked ornamental pond needs:

• Pump: £60 – £600 depending on flow rate required
• Filter box (gravity or pressure filter): £100 – £800
• UV clarifier (kills algae): £50 – £300
• Pipework and installation: £200 – £800

A complete filtration system for a medium koi pond: £500 – £3,000. Running costs for pump and UV: £50 – £200 per year.

Edging and Landscaping

How the pond is finished significantly affects the cost and appearance:

• Natural stone or slate edging: £300 – £1,500 for a medium pond
• Bog garden planting area: £200 – £800
• Aquatic planting (water lilies, marginals): £100 – £500
• Pebble beach edge: £100 – £300
• Formal paving surround: £500 – £2,000

Electricity Connection

Running electricity to the pond for a pump, filter, and lighting costs £300 – £800 for installation (armoured cable from the house or a sub-board). This must be installed by a Part P-registered electrician.

Wildlife Ponds vs Ornamental Ponds vs Koi Ponds

Wildlife pond: No pump or filter required. Plant with native species (water forget-me-not, yellow flag iris, native water lily). Attracts frogs, newts, dragonflies, and birds. Lowest cost and maintenance.

Ornamental pond: May have a small pump for a fountain or waterfall feature. Stocked with common goldfish or orfe. Mid-range filtration. Good balance of interest and manageability.

Koi pond: Koi produce a large amount of waste and need sophisticated filtration, high oxygen levels, and sufficient depth. Japanese koi can cost £50 – £5,000+ each. The pond system needs to match the koi load. Highest cost and maintenance, but a koi pond is a serious long-term hobby for enthusiasts.

Planning Permission and Safety

Garden ponds generally do not require planning permission. However, if you are in a conservation area or have a listed building, check with your local authority.

Safety: A pond poses a drowning risk to young children. If you have young children, consider:

• A mesh cover fitted below the water surface
• A safety grill across the pond
• Converting to a pebble pool feature until children are older

DIY vs Professional Installation

For a wildlife pond under 5m2, DIY is very achievable — the tools required are basic (spade, wheelbarrow, spirit level, flexible liner) and the result can be excellent.

For formal or koi ponds, professional installation is strongly recommended. Errors in concrete construction, filtration sizing, or electricity installation are expensive to correct.