How to build a wildlife pond

Freshwater habitats support an extraordinary range of life — amphibians, insects, birds, small mammals and countless invertebrates. When natural ponds disappear from the wider landscape, garden ponds become genuinely important refuges. And unlike most wildlife features, ponds largely look after themselves once established.

Why even a tiny pond matters

Ponds support more biodiversity per square metre than almost any other garden feature. A single small pond can become home to dragonflies and damselflies, water beetles, pond skaters, water boatmen and other aquatic invertebrates within weeks of being created. Frogs, toads and newts (where present in your region) will find it and use it for breeding. Birds drink and bathe at its margins. Hedgehogs, foxes and other mammals come to drink. Bats hunt insects over open water at dusk.

Across much of Europe and other temperate regions, a significant proportion of ponds that existed a century ago have been filled in, drained or degraded. This loss of freshwater habitat has had a real impact on amphibian populations, aquatic invertebrates and all the species that depend on them. Individual garden ponds, connected across neighbourhoods, form a meaningful network of habitat.

Choosing the right spot

Where you put your pond matters as much as what you put in it. A few key considerations:

• Sunlight and shade balance. A pond in full sun all day will warm up quickly and promote algal growth. A pond in deep shade will not support most aquatic plants. Aim for a spot that gets sun for at least part of the day — ideally a few hours of morning sun with afternoon shade, or dappled light.
• Away from overhanging trees. Falling leaves decompose in the water, releasing nutrients that encourage algal blooms and reducing oxygen levels. Site your pond at least several metres from the drip line of large deciduous trees if possible, or fit a net in autumn.
• Level ground. A pond on a slope is very difficult to build well — the liner will be uneven and one bank will be too deep while the other is too shallow. Choose a level or very gently sloping spot.
• Away from other plantings that may spread into it. Vigorous spreading plants nearby can be difficult to manage once a pond is established.

Size options — from container to dug pond

Do not let lack of space stop you. Wildlife ponds come in all sizes, and even the smallest supports real biodiversity.

• Container pond — a half-barrel, old butler's sink, large washing-up bowl or any watertight container that is at least 30–40cm deep. Buried at ground level so wildlife can access it easily, or with a ramp or stone staircase leading down to the water. These are excellent starter ponds and can support insects, beetles and even small amphibians.
• Small dug pond — any hole dug to at least 40–60cm at its deepest point and lined with butyl rubber, EPDM or pre-formed rigid liner. Even a pond the size of a dining table makes an enormous difference to garden biodiversity.
• Larger dug pond — if space allows, a deeper, larger pond (with a deepest zone of at least 60cm to prevent freezing solid in winter) supports a wider range of species including larger amphibians, dragonflies and bathing birds. The sloped or shelved edges are the most ecologically productive zones.

Construction and the essential ramp

The most important single feature of any wildlife pond — one that is missed in many ornamental fish ponds — is that creatures which fall in can get out again. Vertical sides trap hedgehogs, frogs, birds and other animals, leading to drowning. This is non-negotiable for a wildlife pond.

• For a dug pond: Slope at least one side very gently (ideally a 1-in-3 gradient or shallower) so that creatures can walk out. This shallow margin also creates the most valuable habitat zone — the area where water meets land, where marginal plants grow and where many species breed.
• For a container pond: Use a pile of stones, a piece of rough timber or a purpose-made ramp, arranged so it reaches from below the waterline to above the rim of the container, giving any creature that falls in a route to climb out.
• Liner: For dug ponds, butyl rubber and EPDM pond liners are durable and safe for wildlife. Remove any sharp stones from the base before laying the liner, and use a protective underlay beneath it. Pre-formed rigid pond liners are an easier option for small ponds.
• Edging: Overlap the liner generously over the edges and bury or hide it under turf, flat stones or soil. A bare liner edge deteriorates in UV light and looks uninviting.

Filling your pond

Rainwater is by far the best water for a wildlife pond. It is low in nutrients and free from the chlorine and other additives found in tap water.

• If you have water butts, use them to fill or top up your pond. If not, collect water in buckets or barrels during wet weather.
• Tap water can be used if rainwater is unavailable, but let it stand for a few days before adding plants and wildlife, and expect some algal activity as chlorine levels reduce and the pond ecosystem begins to establish.
• Do not fill your pond from a river, canal or other natural water body — this can introduce invasive species and pathogens.
• Allow a new pond to settle for a week or two before planting, to let the water temperature equalise with the surroundings and any fine soil sediment to settle.
• For rainwater harvesting guidance, see our water conservation resources.

Planting — what to add and what to avoid

Plants are not decoration in a wildlife pond — they are the engine of the ecosystem. They oxygenate the water, provide cover and food for invertebrates, create egg-laying sites for amphibians, and shade the water to reduce algal growth. But the wrong plants can take over and become a serious problem.

• Oxygenating plants — submerged plants that add oxygen to the water and compete with algae for nutrients. Hornwort (Ceratophyllum demersum), water starwort (Callitriche) and spiked water milfoil (Myriophyllum spicatum) are widely available native oxygenators in many temperate regions. Check which species are native to your area before buying.
• Marginal plants — grow at the water's edge in the shallow zone. Native species such as water forget-me-not, brooklime, marsh marigold and native rushes and sedges (depending on your region) stabilise the banks, provide habitat structure and attract insects. Check local guidance for appropriate native marginals.
• Floating-leaf plants — such as native water lilies (in larger ponds), whose floating leaves shade the water and reduce algal growth while providing resting spots for insects and cover for aquatic creatures below. Choose a species appropriate to the depth and size of your pond.

Why not to add fish

This is one of the most important and least-followed pieces of wildlife pond advice: do not add fish. Even small goldfish or common carp will eat the eggs and larvae of frogs, newts, dragonflies, water beetles and most other wildlife that makes a pond ecologically valuable. A pond with fish is essentially a fish tank — interesting, but not a wildlife habitat. A pond without fish will establish a functioning aquatic ecosystem naturally and quickly. If you love fish and want to keep them, consider maintaining two separate water features: one fish pond and one wildlife pond, ideally with no connection between them.

Letting wildlife arrive naturally

One of the great joys of a wildlife pond is that you do not need to "stock" it. Wildlife will find a new pond remarkably quickly, often within days or weeks of filling it.

• Water beetles, pond skaters and other aquatic insects are strong fliers and will colonise new water bodies very quickly. Dragonfly and damselfly nymphs typically arrive within a season.
• Frogs, toads and newts will find your pond in spring if there is a connected population in your area. Never remove frogs or spawn from another pond to introduce to yours — this can spread disease and is best avoided.
• Resist the temptation to add water and plants from other ponds to "kickstart" the ecosystem, as this can introduce disease, parasites and invasive species.
• A patch of longer vegetation or a log pile near the pond edge provides the damp terrestrial habitat that amphibians need when they are not breeding in the water.

Maintenance and topping up

A wildlife pond needs relatively little maintenance once established, especially compared to an ornamental pond with a pump and filter system.

• Topping up: Ponds lose water through evaporation, especially in summer. Top up with rainwater where possible. In a prolonged dry spell, tap water is acceptable but try to add it gradually rather than all at once.
• Autumn leaves: Net the pond surface in autumn to catch falling leaves, or remove accumulated leaf litter from the bottom periodically. Decomposing leaves consume oxygen and add nutrients, which can cause problems in smaller ponds.
• Managing plant growth: In established ponds, oxygenating plants and marginals can spread vigorously. Remove excess growth in late summer or early autumn, doing this in stages and leaving removed plant material at the pond edge for 24 hours so any creatures can return to the water.
• Green water: Algal blooms (green or murky water) are common in new ponds and in spring when nutrients are high. They usually clear naturally as oxygenating plants establish and shade the water. Do not use chemicals or algaecides in a wildlife pond.
• Ice in winter: A wildlife pond does not need to be kept ice-free. Most pond life survives under ice in a reasonably deep pond. If you are concerned, float a tennis ball on the surface — when removed, it leaves a hole in the ice that allows gas exchange. Never smash ice or pour boiling water on it, as the shockwaves harm pond life.

How to build a small container pond

1. Choose a container. A half wooden barrel, large ceramic planter (plug the drainage hole with waterproof sealant), butler's sink, or purpose-made container pond kit all work well. It should be at least 30–40cm deep and hold a good volume of water — the larger the better.
2. Choose the site. Level ground with a mix of sun and shade — a spot that gets a few hours of sunlight daily but is not in full sun all afternoon. Keep it away from overhanging deciduous trees.
3. Bury it or create a ramp. If possible, sink the container to its rim in the soil so that ground-level creatures can access it naturally. If it must stand above ground, build a permanent ramp or staircase of stones leading from the ground to the water surface inside.
4. Add a wildlife escape ramp inside the container. A rough stone or piece of wood wedged at an angle from the base to just above the waterline gives any creature that falls in a route out. This is essential.
5. Fill with rainwater. If using tap water, let it stand for a couple of days before planting.
6. Add native oxygenating plants. Place them in mesh baskets weighted with aquatic compost and gravel, lowered to the bottom or on a shelf of bricks inside the container. Add one or two native marginal plants on a raised shelf of bricks near the rim where the water is shallower.
7. Add stones or gravel around the rim for insects to land on and to bridge the gap between the container edge and the water surface, creating perching spots for dragonflies and drinking spots for birds and bees.
8. Wait. Leave the pond to establish. Check the water level weekly in summer and top up with rainwater as needed. Your first visitors — water beetles, pond skaters, midges — may arrive within days.

Your wildlife pond checklist

• Choose a level, partly sunny spot away from overhanging trees.
• Build in at least one gently sloping side or ramp so all creatures can escape.
• Fill with rainwater where possible; if using tap water, let it stand first.
• Plant only native oxygenators, marginals and floating-leaf plants.
• Never add fish to a wildlife pond.
• Do not source plants or water from natural water bodies to avoid introducing invasives.
• Net the pond in autumn to catch falling leaves.
• Leave a damp log pile or long vegetation near the pond for amphibian habitat.