Making a garden pond – how to build a pond in the garden

If you own a pond or a larger water container, you can enjoy many exciting aquatic plants, such as swamp plants, floating plants, underwater plants and water lilies. 

Aquatic plants are not only beautiful to look at, many also help to keep the water clean. For example, floating plants provide shade that reduces algae blooms, and the leaves of underwater plants can absorb excess nutrients. There is a wide range of exciting and interesting aquatic plants.

Read our article about aquatic plants and water in the garden for good tips and advice.

Choose a flat area when placing your pond. You should also avoid placing it in the hottest part of the sun and not right next to trees, where a lot of leaves fall. Be aware that you may encounter large rocks and the like if you dig near mountains. If you don't want to resort to blasting or hiring a large excavator, it's a good idea to investigate the conditions quite thoroughly before you start.

Decide on the shape of your garden pond, whether it should be large or small, wavy or perhaps sharply geometric. The pond can also have different expressions depending on the plants you choose to plant. Do you want something soft and romantic in the English style, or a stylish square bordered by ornamental grass? Play with different shapes and plants until you find a style that suits you. 

There are also pre-formed ponds, made of hard plastic, with a predetermined appearance. Unlike an excavated pond, the molded pond is placed on a gravel base that is leveled. Use a spirit level to ensure that the base is level. Fill the bottom with about ten centimeters of water and fill in the substrate on the outside.

Regardless of the shape of your pond, it is practical to start in the middle and dig out towards the sides. Dig about 5 cm deeper than you intend the pond to be, so that there is room for decorative stones and planting material. 

If you are building a larger pond, you can make it have varying depths to be able to plant a variety of plants with different needs. For example, it can be 50 cm deep in the middle and 10–15 cm closer to the edge. 

Remember that the pond should be level to get a nice result. If one side is higher than the other, you will see more of the fabric and edge on the shallow side. There are special edge bands that you can install around the edge to get a nice finish and something stable to lay the fabric against, such as Ecolat edge band.

Usually, a protective mat is placed at the bottom of the pond, or alternatively, you can lay a thick sand bed. It is important that there are no sharp stones or protruding roots left, as these can damage the protective mat.

Then, you put in a pond liner – there are both adapted UV-resistant plastic (PVC) and thicker, more elastic rubber liners. If the pond liner needs to be joined, use a special type of glue. If, on the other hand, you have a rubber liner, use primer and double-sided tape for the best result. Fill in with soil or sand on the outside.

You can place a coconut mat on the pond liner that extends slightly over the edge. The coconut mat acts as a substrate for the plants and at the same time hides the rubber liner until the plants have established themselves. The coconut mat can in turn be covered with sand, gravel or aquatic plant soil, depending on which plants you want. It is available as an edge mat. Another option for hiding the liner is a stone mat. This is suitable in areas with a steep slope or in streams.

Tip! Plants with high nutrient requirements, such as water lilies, can be planted in special plant baskets with aquatic plant soil specially adapted for them.

Feel free to fill the pond with rainwater or seawater, as this provides a good ecological balance from the start. A small stream or a dug imitation stream from the gutter can also be used to supply the pond with water, and you can also plant aquatic plants along it.

A small fountain or similar will make the water surface move, making it more difficult for mosquitoes to lay eggs.

To keep the water clean and clear, choose a filter and pump that are adapted to the water volume and conditions in your pond. 

You can calculate which system is suitable based on the water volume (size of the garden pond). The pump capacity is measured in liters per hour (l/h). As a general rule, a pump should be able to circulate the entire pond water volume at least once every two hours, so that oxygen is added and kept moving to keep the water fresh. For a 2000 liter pond, you should have a pump that can handle at least 1000 l/h. For smaller ponds, it is possible to choose a solar pump, so that you are not dependent on a power outlet. 

There are different types of filters, such as mechanical filters, biological filters (often used in planted ponds) and UV filters. Mechanical filters capture larger particles, while biological filters use bacteria to break down harmful substances. UV filters use ultraviolet light to kill algae and bacteria. If the pump has so-called UV-C light, you avoid green water, for example. If the filter has a backwash, the need to remove and wash the filter is reduced.

If you are going to have fish, or if you are planning to swim in the pond, this means a higher load on the system, and then you need a more powerful installation. Fish ponds, especially those with koi, require more powerful filtration systems because the fish produce waste that needs to be filtered out.

Also think about any accessories that may be needed, such as hoses, connectors and perhaps a fountain or waterfall for extra oxygen, life and movement.

Consider carefully where you place your pump and filter. The pump should be placed so that it can circulate the water efficiently, and the filter should be easily accessible for cleaning and maintenance.

Some people bury the filter outside the pond, or build it in so that it is not visible. However, many filters should be brought inside in the winter to avoid frost damage, so place it easily for cleaning, but also easily accessible so that you can bring it inside for storage.

If you want a fountain in the pond or a small waterfall, you need a special pump. For those who want a fountain or waterfall, there are fountain pumps that are a good alternative, and for those who want a stone fountain or a figure fountain, there are water stone pumps. These pumps are designed for this purpose and therefore have a design and performance that suits the task. 

Today you can also buy floating fountains and air pumps – for better oxygenation and water quality.

For those who want to have fish in the water, koi or carp are the most common, but they are likely to eat the eggs of wild frogs and salamanders, so if you want to support wild species, fish are not the best choice. A more powerful purification system is also required, as mentioned, and the garden pond needs to be quite large for it to work.

Children can drown, even in shallow water. So always keep an eye on small children, and consider putting up a fence around the pond. Also, leave one side shallow, or add a rescue board so that any animals like squirrels and dogs can get out if they accidentally fall in. 

Finally, enjoy the water in your garden!

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