How to build a garden pond

Your garden is the blank canvas onto which you will plan your new pond. Every garden is unique, with opportunities and constraints as to where you can site a pond.

A pond should be planned primarily where it will be viewed and enjoyed the most, and if you have been contemplating a pond for some time, you may well already have decided your preferred position.

If you are planning a formal, geometrically-shaped pond, then the existing structure of your garden will determine the pond’s position. If you prefer an informal and irregularly-shaped pond then to look convincing, it should appear as though nature placed it there. The final position of any pond in an existing site is likely to be a compromise between aesthetic and practical considerations. These will not only determine where the pond is finally located, but will also affect its final size, shape and even its performance.

Choosing a site.

Viewing points.

Unless you are planning your pond to be a secret aquatic oasis, hidden away at the back of your garden for the wildlife to enjoy, then a pond is installed as a definite feature of a garden. It is to be viewed and enjoyed. Whether your preferred viewing point is your favourite garden bench, from within your conservatory or through your kitchen window, you need to establish where your main viewing point will be. Other practical factors relating to the pond’s excavation and installation and subsequent maintenance will determine whether your preferred site works, or whether it needs to be moved slightly as a compromise.


Sunlight is essential for a thriving and vibrant pond. A pond should be positioned so that the sun hits it for half of the daylight hours. This will help a pond achieve a productive and stable temperature that will benefit the fish and other aquatic life. Aquatic plants will also thrive and flower well in a sunlit pond, with lilies especially requiring generous sunlight to flower well. If a pond receives too much sun each day then it will be prone to developing algae problems as well as undesirable swings in temperature. If your site is unavoidably sunny for the majority of the day, then you could consider erecting a pergola to give shade.

Existing Garden Features.


In nature, you will often find trees growing adjacent to a pond or stream, enjoying the beneficial growing conditions. In a garden, having a pond immediately adjacent to a tree is less desirable for several reasons:

1. Excavation. Planning a pond on paper is far easier than digging it out – especially if that means cutting through tree roots. If during the excavation you encounter tree roots, you will have no option but to cut through them (however thick), making an arduous digging job even harder. Cutting through roots is hard work, not good for the tree and the tree may well retaliate in years to come by puncturing the liner with new roots.

2. Shade. Your pond and any existing trees are likely to be there for many years. As the trees continue to grow, they are likely to deny the pond of essential sunlight, affecting the life and growth of pond plants.

3. Leaves. Overhanging and adjacent trees will drop leaves, fruit and even twigs into a pond. If these are allowed to fall into a pond to decay, they will adversely affect the water quality, reducing dissolved oxygen levels and with the accumulation of nutrients encourage nuisance algae. Evergreen trees and shrubs can also pose a similar problem, dropping smaller leaves or needles all year round. These prove to be stubborn at breaking down and can be so fine that they will even pass through a pond net. I believe that as soon as you have to cover a pond with a net, the whole effect that you are trying to create with your pond is lost. Some trees should be avoided because they are potentially toxic to fish. These include: willow, yew, holly and laburnum.


If your proposed position for your pond takes it near existing buildings, including your house, then there are several factors to consider.

1. Footings and foundations. Make sure when planning the position of your pond that you allow sufficient space to avoid foundations during the excavation. Excavating close to adjacent buildings could also encourage subsidence. If the building is temporary (such as a shed or a greenhouse) and you would consider moving it to get your pond in the best position, then do so. It’s better to build a pond of the desired size and position than compromise on its position, potentially affecting its performance for its lifetime.

2. Electricity and drains. The closer you excavate to a building, the greater the risk of intercepting existing immoveable services. Do as much preliminary investigation as you can when planning and especially before you start to dig.

3. Neighbours. It is quite likely that your pond will include the sound of running water. This is one of the many sensory benefits of adding a pond to a garden. A waterfall or fountain will produce a continuous sound of running water, which to you may be therapeutic and appealing, but to a neighbour, may prove be an intrusive annoyance. You should consider how your neighbour may respond to the sound of running water coming from the garden next door, and it may be wise considering installing a separate pump for a fountain or waterfall that can be switched off at night, leaving a pump circulating the water through a filter.

Lie of the land.

Most gardens are flat. This presents us with a challenge of how to incorporate a waterfall or stream. A convenient way of using the spoil from the excavation is to pile it behind the pond and use it as a raised area for siting a waterfall or stream. There is a big risk that an isolated raised area could look contrived (and very unnatural), especially if placed in a central location in the garden. A good solution is to pile the soil and site a waterfall or stream against a garden wall or boundary. If you choose not to have a waterfall or stream in a flat garden, then you will be faced with the arduous task of removing the spoil from your garden.

If you are fortunate enough to have a sloping garden, then this feature can be used very effectively. With the high ground sloping down towards the viewing point, the naturally-occurring gradient will allow you to construct a plausible stream that appears in a spring-like fashion and then feeds a pond, cut into the slope of your garden.


Once you have narrowed down your preferred location, the final thing to establish is the position of existing services (electricity, gas, drains etc) that might travel under your proposed pond. If they do, you need to establish whether they can be moved, otherwise your pond will have to move. You will also need to get an electricity supply out to your completed pond for the pump and even some lighting. You should be satisfied that the location of your pond allows the safe laying of a new cable out to your pond.

The visualisation

Having taken on board all of the aesthetic and practical considerations, you should plan out the desired size and shape of your pond in-situ in your garden. Lay out a rope or hose pipe, walk around it, view it from every angle for several days. Look for how it may be affected by undesirable reflections on the water. Plan where the power will run and make allowances for where any spoil may go. You also need to plan where the pond’s filter will be situated. Having had a few days to tweak and reconsider, seeking advice from the family, now comes the hard work of excavating the pond.

Quick checklist

Where to site your pond.

Viewing point:

Locate the pond where it is going to be viewed most frequently. If there is going to be a waterfall, then this should be constructed to the back of where the pond is going to viewed. If your land is sloping, to look natural, an informal pond will be best sited at the lowest point.


Tree roots can cause problems during excavation and by possibly piercing the pond liner in years to come. Trees will also drop leaves all year round, but especially in autumn. These will breakdown in the pond and unbalance the natural ecosystem you are trying to achieve. Avoid siting the pond near willow, yew, laburnum, holy or any evergreen trees, as these can prove to be toxic to fish and other pond life.


Sunlight is an essential ingredient for a successful pond. Too little and it will not thrive. Don’t plan your pond too close to anything that will cast permanent shade (fence, shed, house, trees). Check the shadows across your garden when the sun rises and sets. Avoid a north facing garden that is shaded from the sun. Lay out a hose pipe or rope to mark out the shape and position of your pond. Check during the next few days that it received sufficient sunlight and that it can be easily viewed from your favourite viewing points.


Once you have established the best place for the pond, check that there are no services (gas, water, drains, telephone, electricity) running underneath. Confirm that it is also feasible to reach your pond safely with electricity for the pump and lighting.

Visualise it.

Kill blanketweed and string algae.