There are four options to lining a garden pond one of which is to use a flexible pond liner such as PVC, Butyl or Epalyn (EPDM). Other choices are preformed – also referred to as moulded ponds, concrete or natural materials. A pond liner is the most popular choice offering great design flexibility, however if not installed correctly it risks being punctured and requiring repair. To full proof (i.e. greatly reduce the risk of water lose through leakage) your garden pond build, first install a protective underlay to more than double your pond liners life expectancy. 

A protective pond underlay will protect the liner against sharp stones and roots before laying it in the pond recess. The most commonly used protective underlay liner these days is a geotextile fabric made from non-woven polypropylene or polyester which has been needle punched to give it a felt-like texture. The material is extremely tough and will give a high degree of protection. Importantly, it will also last as long as the pond liner itself, unlike some of the home-made alternatives such as layers of newspaper and old woollen carpets. 

Benefits of a protective pond underlay liner

• enhances soil stability and prevents erosion
• protects pond liner from roots, rocks and other sharp objects pushed up due to ground movement
• provides additional tear and puncture protection

Other protective functions of a pond underlay 

What is less well known is that geotextile protective liner can also be used as an overlay liner – and there are several reasons why this would be an advantage to your pond build. The main area where an underlay is used as a protective overlay is on top of the lining around the edge of a pond, where the flexible lining rises out of the water and lies on top of the surrounding soil or collar. Here an additional layer of geotextile protective pond underlay is placed on top of the liner before the stones or slabs, that will form the border of the pond, are put in place. Similarly, if your pond design features an underwater shelf or platform for shallow water plants, those areas too should use a protective overlay. The presence of an overlay liner can also provide some protection against the sharp claws of pet dogs or cats – and even the stab of a heron’s beak. 

A pond underlay liner should be fit for purpose to extend the life of a pond liner. Trying to skimp on budget by using other materials such as old carpet cut-offs or newspaper which will rot over time thereby risking greater expense carrying out pond repairs. Pond underlay is not an expensive investment relative to the total cost of a pond provided you make your purchase from a reputable pond supplier. 

A pond underlay is key to ponds intended to be lined with a pond liner – to order yours, visit our website and if not sure what dimensions to order, you can use our pond liner size calculator and input the exact dimensions of your pond and the calculator will do the rest – Pond Liner Size Calculator