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A nicely laid out pond is a decorative eye-catcher in the garden, but only if it is well filled and the foil used is not visible. If the water level drops rapidly, a pond quickly loses its attractiveness. You should definitely do something about this. Fortunately, a hole in the pond is not always to blame, there are numerous other reasons for a sinking water level.

water level

How far can the water level drop?

Some evaporation is completely normal in summer. If the water level drops by a maximum of two to three centimetres, simply refill the missing water. There is no reason to worry. If you have fish in your garden pond, make sure that the fresh water has about the same temperature as the water in the pond. In this way you avoid a temperature shock in the animals, which in the worst case could be fatal.

Plants in the garden pond

water loss

Why is my garden pond losing too much water?

The reasons for water loss vary depending on the season. In summer, excessive evaporation could be the trigger. This is caused by extreme heat, but also by very dense bank vegetation. If you notice an extremely low water level in late summer or autumn, then check how much your aquatic and riparian plants have grown.

If you have only recently created your garden pond, then the reason for the low water level may be a construction error that triggers the so-called capillary effect. A broken or leaking filter system can also lead to a low water level, as can a hole in the pond liner.

capillary effect

What is meant by capillary effect?

If you covered the edges of the pond liner with soil or did not lay the liner high enough, this soil will suck moisture out of your pond like a sponge and the water level will drop. A relatively sure indication of this capillary effect is a swampy bank area. Incidentally, the capillary effect also comes into play in winter, but this is usually only noticeable in the spring when the ice on the garden pond has melted.

Getting to the bottom of water loss step by step:

  • abnormally low water level
  • Check bank vegetation and thin out if necessary
  • rule out design errors
  • possibly install a capillary barrier
  • Check the filter system for leaking hoses
  • possibly repair
  • Check pond liner for holes
  • glue foil

Holes in pond liner

How do I find holes in the foil?

Depending on the size of your pond, finding what may be a small leak can take a long time, especially if the leak is relatively deep. It is best to first fill your pond to the brim with water. Now mark the current water level on the pond liner every day. Initially, the level will probably drop quite quickly, but over time only slowly or not at all.

The responsible hole through which your garden pond loses water must be at this height. Thoroughly clean the area in question. You might spot the leak if it's big enough. If not, feel that area thoroughly and see if anything is pushing through the foil.

Common reasons for holes in the foil:

  • sharp stones
  • old shards of glass or pottery
  • Plant rhizomes, for example of bamboo
  • wrinkles in the foil
Pond in the garden provides a home for plants and animals


How can I repair my garden pond?

Before you can patch any holes in the foil, you must first dry this area. So drain enough water from your garden pond so that you can work in the dry and the leaking area can be taped over a large area. You can find special repair kits for garden ponds in specialist shops. Before you buy such a set, make sure you know which liner you used to build your pond.

You may have to move the fish and/or water plants in the garden pond while the repairs are being made. So you have enough space for the necessary work. Depending on the film used, this work is more or less complex. In any case, remove the cause of the leak, otherwise your garden pond will be leaking again in a short time. After the repair, wait at least 24 hours before refilling the pond with fresh water.


Gluing PVC film

You can patch PVC film with a waterproof PVC adhesive. Before doing so, however, the film should be thoroughly cleaned. Cut out the required patch generously from existing or new PVC film. Coat the areas that are to be glued together with the special PVC glue and press the areas firmly together. You can easily remove any trapped air bubbles with a small roller or wallpaper roller.

A means for particularly easy patching or areas that are difficult to access is PUR liquid pond liner. However, it is not the cheapest method. You should apply at least three layers of this liquid liner so that your pond does not leak again in a very short time and lose water again. Allow the individual layers to dry well before applying the next layer of liquid foil, this will make the repaired area more stable and durable.

PVC foil is cheaper to buy, but unfortunately does not last as long as EPDM foil. If it is already quite old, then it may have become a bit brittle. If more frequent repairs are necessary within a short period of time due to water loss, then you may think about a complete replacement.

Garden pond with fountain


Repair EPDM foil

The EPDM foil must also be thoroughly cleaned with a special agent before the repair. Cut a sufficiently large patch from leftover film if you have any in reserve. Then spread the adhesive from the repair kit onto the foil and the patch. It should then act for five to ten minutes.

Glue double-sided special adhesive tape for rubber foils to the patch prepared in this way. Never use normal double-sided tape, it is not elastic enough. Then stick this patch to the EPDM foil on the pond without any creases. You should be able to press down easily with a wallpaper roller.


How can I protect myself from water loss in the future?

To ensure that your garden pond is always well filled in the future, you should avoid everything that causes the water level to drop too quickly. Check the planting regularly and cut back excessively lush bank vegetation in good time, preferably in autumn. This reduces evaporation for the next winter. In the spring, you can also divide plants that have grown too large, such as cattails or reeds. Perhaps you will find grateful buyers in your family or circle of acquaintances.

If the capillary effect was the reason for the low water level, use a capillary barrier. Check the filter system regularly. If a hose is cracked or leaking, replace it immediately. The same applies to defective or incorrectly installed connections.

Water inlet of a garden pond

capillary barrier

How do I set a capillary barrier?

It is best to create a capillary barrier when constructing the pond, because then the work involved is relatively small. Cut the PVC or EPDM foil very generously. Dig a ditch about 15 centimeters wide around the pond basin. It should be about 15 to 30 centimeters deep. Line the pool and trench with the liner and fill in coarse gravel. You can also use lean concrete instead of gravel or build this barrier out of concrete slabs.

If you have failed to create a capillary barrier, you can also build this barrier later. If the foil used is large enough, then proceed as just described. If your liner is not sufficient for the required ditch, you can use a prefabricated pond edge system. The plastic profiles, which are around 14 to 20 centimeters high, are commercially available by the meter. There are matching plastic posts for this.

Drive the stakes into the ground about 50 to 60 centimeters apart around your garden pond. If the distance between the posts is too large, the profiles could be pushed outwards by the water pressure. Next, attach the profile tape to the posts with screws. You can use a spirit level to check the correct position of the profiles and adjust them if necessary.

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