How to make a pond in your garden

Making a pond is by far the best way of boosting wildlife - not only are you providing a new kind of habitat to attract different plants and animals, but you are also giving existing wildlife more food and shelter. Becca Cleaver from Pond Conservation tells us how...

Inch for inch, it is probably the richest wildlife habitat you could create in a garden, and easily the most fascinating.

Get a good water supply

You should start planning your own pond by investigating the water supply. Clean water is crucial, and by understanding where the water will come from, you can keep out the pollution and capture clean water.

Dig a test pit, as deep as you can, to find out what kind of soil you have, and how deep the natural water level is. Observe the water level changes through a whole year if possible. If the soil and water levels are suitable, you may not need to use a pond liner.

If the pond is in a garden you can make use of the rainwater from the house or garage roof, but be wary of using a stream or ditch to feed the pond as they are frequently polluted

Don't use tap water for your pond - not only is it wasteful and unsustainable, but it also has high levels of plant nutrients and will lead to more problems for you and the pond.

Choose a good location

If you have a choice of where to make your pond, locate it close to other ponds, streams, marshes, lakes etc. Being close to other wetland habitats increases the number of plants and animals that could colonise your pond, and increases the speed at which they arrive.

Important legislation

Depending on the size and location of your new pond, you may have to get consent from various public bodies before you start work. Small garden ponds normally don't require permission. For other projects, you may need to talk to the local planning authority, the Environment Agency, the County Archaeologist, the Highways Agency, the local authority Rights of Way Officer or Natural England.

Does size matter?

It really doesn't matter whether your new pond is one metre or 20 metres across - it will still be a valuable wildlife habitat. In fact, creating some small ponds and puddles where there are already large ponds, or vice versa, can be a great boost for wildlife.

Make the most of the space you have got, and if you have lots of space, consider making several small ponds instead of one large one.

Vary the design

"Take into account how the water levels will change and make sure there will be shallow margins."

If you have space to create more than one pond, make them all a bit different in size, shape and depth to maximise the range of wildlife they can support. If you are making one pond, include as much variation as you can. Make the pond edge wiggly, with lots of very shallow areas just a few centimetres deep, and bumps and hollows - this will be the most wildlife-rich part of the pond. Take into account how the water levels will change and make sure there will be shallow margins whatever level the water is at.

Types of pond liner

It is easier and cheaper to create ponds in naturally water-retaining soils where a liner isn't need, but this isn't always possible. Pond liners can vary in ease of use, flexibility, longevity, cost, and naturalness. For a good wildlife pond, you want a liner that will allow you to create large shallow margins and a varied shape, and preferably a natural substrate (soil or gravel) for plants and animals to live in.

PVC or butyl rubber liners are easy to use, especially for small ponds, but do have some drawbacks: they are easily punctured and difficult to repair, they degrade in sunlight and have a limited lifespan, and they don't hold soil on slopes, leaving nowhere for plants to root. Ideally, plastic and butyl liners are laid over a cushioning layer of geotextile, sand or old carpet to protect it from sharp objects, and covered by another geotextile layer to protect if from sunlight and help soil and plants keep hold.

Geosynthetic clay liner, a carpet-like material made of bentonite clay sandwiched between two geotextile membrane layers, avoids a lot of these problems. It self-seals around punctures and, because it is buried under 300mm of soil, the pond can be shaped to maximise wildlife. The liner is invisible, so it looks natural, and it provides a natural substrate for plants and animals to live in. However, experienced contractors should be used to line larger ponds with this material.

Filling up

Filling a pond with water is not normally necessary, and can introduce some new problems. Using tap water will introduce a flush of nutrients, increasing the risk of algae blooms. Pumping in water from a pond or river can introduce pollutants, fish or invasive plant species, undoing all your hard work to make it a good wildlife pond. The best source of water is the rain or ground water that will be the pond's normal water supply, but you may have to wait patiently for it to fill up.

To plant or not to plant

It is natural to think that ponds need a helping hand to develop vegetation, but in fact it is usually unnecessary as many pond plants and animals are well adapted to finding new ponds, and surprisingly quickly. Pond surveys show that three or four year old ponds are often as rich as 50 year old ponds, without any help!

The plants and animals that do colonise a pond under their own steam are usually more appropriate to the pond and local area than those you might choose yourself. Letting the plants and animals arrive naturally also avoids one of the major problems of planting-up ponds: the introduction of invasive non-native plants. The accidental introduction of fish is another problem.

Another reason not to plant up ponds is that new ponds are a very distinct habitat, needed by plants and animals that don't like more established ponds, either because they need the bare soil or don't compete well with other species. By artificially ageing the pond, you are missing out a whole stage of pond life.

Pond Conservation