Pond Liner Underlay

Find out more
Pond Liner Underlay

Pond Liner Underlay

Pond liner underlay is one of the most important parts of a reliable pond build. It sits beneath the pond liner to help protect it from stones, roots, rough ground and other puncture risks, reducing the chance of damage once the pond is filled and finished.

Quick choice: Use standard 250g/m² underlay beneath the pond liner. Use black 250g/m² underlay / overlay where the material may be visible or where stonework is being placed above the liner.

Our 250g/m² pond liner underlay is a dense, protective geotextile-style material supplied from a 2m wide roll and sold by the linear metre. It is suitable for use beneath Greenseal EPDM pond liner, Elevate PondGard / Firestone EPDM pond liner, Butyl rubber pond liner and PVC pond liner.

We strongly recommend using pond liner underlay on almost every pond build. It is a small extra cost compared with the cost and disruption of replacing a punctured liner, and it is especially important where the ground contains stones, roots, sharp edges or compacted soil.

Pond Liner Underlay Features

  • Protective 250g/m² pond liner underlay
  • Supplied from a 2m wide roll and sold by the linear metre
  • Helps protect pond liners from stones, roots and rough ground
  • Suitable for use beneath EPDM, Butyl and PVC pond liners
  • Useful for garden ponds, koi ponds, wildlife ponds, streams and waterfalls
  • Can also be used above the liner where stonework may rub against the liner surface
  • Black underlay option available for more discreet overlay protection

Why Use Pond Liner Underlay?

Pond liner underlay helps protect your pond liner from damage caused by stones, roots, rough soil and sharp ground beneath the pond. Once a pond is filled with water, the weight pressing down on the liner is considerable, so even small stones or hard points in the ground can become a long-term puncture risk.

For this reason, we normally recommend underlay as part of the pond build rather than as an optional extra. A good liner is only as well protected as the ground preparation beneath it.

Where Should Pond Liner Underlay Be Used?

Underlay is normally fitted between the excavated pond base and the pond liner. It should cover the base, shelves and sides of the pond so that the liner has a protective barrier behind it.

Underlay can also be useful above the liner in areas where rocks, slabs, edging stones or decorative stonework may rub against the liner surface. This is especially useful around waterfalls, streams, pond edges and areas where stone is being placed directly against or close to the liner.

Standard Underlay or Black Overlay?

Product Best For Main Benefit Things To Consider
250g/m² Pond Liner Underlay General protection beneath pond liners Dense protective underlay to help guard against roots, stones and puncture risks Best used beneath the liner where it will not normally be visible once the pond is finished
Black 250g/m² Pond Liner Underlay / Overlay Use beneath liners or above liners under stonework More discreet black finish where the material may not be fully covered Particularly useful as an overlay above the liner where stonework or rocks may rub against the liner surface

Which Pond Liners Should Be Used With Underlay?

We recommend using pond liner underlay with all main types of flexible pond liner, including Greenseal EPDM, Elevate PondGard / Firestone EPDM, Butyl rubber pond liner and PVC pond liner.

Underlay is especially important for koi ponds, larger ponds, wildlife ponds, ponds with shelves, and any pond where stonework, roots or rough ground may increase the risk of liner damage.

When Should I Use Underlay Above The Pond Liner?

Although underlay is most commonly used beneath the liner, it can also be used above the liner as an additional protective layer. This is useful where rocks, paving, coping stones or decorative stonework are being placed on top of or close to the liner.

The black pond liner underlay / overlay is particularly useful for this because it is more discreet if it is not fully covered by stonework.

Ask a question

If you need to ask a question about Pond Liner Underlay you can do so here.

Do I need pond liner underlay?

Yes, we strongly recommend using pond liner underlay on almost every pond build. Underlay helps protect the pond liner from stones, roots, rough soil and other puncture risks beneath the pond.

What does pond liner underlay do?

Pond liner underlay provides a protective layer between the ground and the pond liner. It helps reduce the risk of punctures caused by sharp stones, roots, compacted soil or uneven ground.

Can I use old carpet instead of pond liner underlay?

We do not recommend using old carpet as a substitute for proper pond liner underlay. Carpet can rot, hold contaminants, break down over time and may not provide consistent protection. A purpose-made pond liner underlay is the safer choice.

Should underlay go under the liner or over the liner?

Underlay is normally installed beneath the pond liner, directly over the prepared soil. It can also be used above the liner where rocks, slabs or decorative stonework may rub against the liner surface.

What is black pond liner underlay used for?

Black pond liner underlay can be used beneath the liner, but it is especially useful as an overlay above the liner where the material may remain partly visible under stonework. The black colour makes it more discreet than standard underlay.