What are the alternatives?

Disadvantages of PVC films

There are enough concerns about the PVC film usually used for pond construction:

• the plasticizers and other substances contained can evaporate
• PVC film is a significant burden on the environment, and its disposal even more
• In fish ponds or ponds with aquatic life, the use of PVC film is very questionable
• PVC changes chemically when the plasticizers evaporate and becomes brittle
• Repairs to PVC foils are often no longer possible after a few years because of the change in material

In most cases, concerns about PVC film mainly concern the environmental aspects of PVC and the possible health effects, for example on aquatic life.

EPDM as an alternative

The much more expensive EPDM foil is already an excellent alternative to conventional pond liners:

• it is significantly more environmentally friendly and does not emit any harmful substances
• it remains highly flexible even in the cold
• it is extremely stretchy (up to 300% stretchability)
• it is highly tear-resistant
• it has an extremely long service life (up to 50 years, often a 20-year guarantee)
• it is easy to misplace
• it can be easily repaired at any time with liquid pond liner

As an ecological alternative, EPDM film is also highly recommended due to its technical properties.

Liquid foil as an alternative

Liquid foil is now used almost exclusively as a repair material. But it can also be used as the sole seal.

Due to its extremely high flexibility, it adapts perfectly to the shape of the pond, is safe for drinking water and does not harm living beings in the pond. Its elasticity is even higher than that of EPDM (up to 400%) and it is even more tear-resistant. However, it can only be used on very smooth surfaces - such as concrete or tiles; alternatively, smooth stones are sometimes also possible.

The content of polyurethane and silane-modified polymers (SMP) may still make some people questionable when it comes to environmental compatibility and naturalness.

Clay seals

The pond is sealed by a clay barrier, very similar to how you do it with walls. For this you can either use damp clay blocks or swelling clay granules.

As a dry material, swelling clay granules are considerably lighter than wet clay and combine by themselves to form a stable layer of clay when they get wet. The clay blocks, on the other hand, first have to be tamped together to form a stable layer of clay.

The necessary layer thickness is at least 15-20 cm, the soil underneath must be compacted. After the granulate has been introduced, it is covered with around 10 cm of sand, and a fine layer of gravel is then added to stabilize it. The granulate is then first moistened and then slowly poured in with the water. The barrier layer is sealed after around 5 hours.