Which Is Best: Preformed Ponds Or Lined Ponds?

One of the most important decisions when creating a new garden pond is how you line the pond. In most cases, this boils down to two choices: a preformed pond, or with a pond liner.

Preformed ponds are a rigid mould, which is made with a non-toxic material which won’t harm plants or aquatic creatures, such as fibreglass, plastic, or rubber.

Pond liners are made from a tough and flexible material, typically a non-toxic synthetic or natural rubber. They are durable enough to withstand impacts from rocks falling into the pond. Look for UV resistant materials that are designed to cope with a wide temperature range

There’s no right or wrong option, and there are benefits and disadvantages to both. Here’s a look at which might be right for you.

Advantages of preformed pond liners

A wide choice of shape

They are available in a wide range of shapes and sizes, from natural asymmetrical forms which imitate nature, to oval or rectangular shapes for more formal gardens.

Extremely durable

They are made to be durable and will withstand impacts, such as rocks and branches falling in, or tree roots pushing up from beneath. They are temperature resistant, and will not degrade in extreme heat or cold. You can expect a preformed pond liner to last for many years.

Easy to install

Preformed ponds are very easy to install. You don’t have to worry about digging a hole that is exactly the same size and shape as the liner. As long as it is deep and wide enough, you can install the pond and backfill the gaps afterwards.

Disadvantages of preformed pond liners

Limited sizes

If you want a very large pond, you may be pushed to find a preformed liner, as most go up to a maximum of 1,000 litres capacity. Likewise, if you have a very specific shape for your pond in mind, maybe to fit in with your garden design scheme, or to fit into an awkward space, you are more limited in choice.

You can’t alter the pond once it’s installed

Once it’s in, you won’t be able to make the pond bigger or change its shape, so you need to be sure about what size and shape you want from the beginning.

Badly designed planting areas

Preformed ponds often have badly designed shelves which may be the wrong depth or very narrow, making it difficult to accommodate a range of planting baskets.  The area of the shelves may also be very small which will unduly restrict the number of plants that can be used.

Finally, some have a so-called bog area around the pond which is superficially a nice idea, but wholly impractical as the planting area is both shallow and narrow and not fed from the pond.  It will not accommodate many plants and will rapidly dry out.

Moving out of place

Occasionally, if a preformed pond liner is not full enough, it may rise up out of its place.

Made in china

Nearly if not all preformed ponds will be made in China.  If nothing else this means a very high carbon footprint.  It is much easier to buy UK made pond liner.

Advantages of pond liners

More freedom of choice for size and shape

One of the biggest advantages over a preformed liner is that they are more flexible, so you can dig out your pond to any size and shape that you wish. If you want to alter it in the future, then you can do this by draining the pond and moving the liner around. Two liners can even be joined together to extend the pond if you wish.

It is important to remember that a pond should imitate nature for best results, with ridges and shelves to promote healthy bacteria growth, place marginal pond plants on and to help wildlife enter and get out of the pond.

Easy to incorporate a bog area

When specifying the size of the pond, additional liner can be allowed for to seamlessly create an adjacent bog area fed naturally by the overflow from the pond.

More affordable

Flexible pond liners are usually cheaper than preformed ponds, so if you are on a tight budget, this may be something to bear in mind.

Long lasting

The best liners, made from butyl rubber will have a working life in excess of 50 years

Disadvantages of pond liners

More work to install

You’ll need to be more precise when excavating the hole for a pond liner, as how you have dug it out is the way it will stay when the liner is installed. Although liners are made from tough material, they are more prone to tears and punctures than pre-formed liners. Therefore, keep a vigilant eye out for sharp rocks and stones when you are digging.

May puncture more easily

Be aware that tree roots may spread and puncture the liner, so if you have positioned the pond near a tree, take some extra precautions. Placing old carpet or underlay, or even a thick layer of newspapers, underneath the liner can give that extra layer of protection.  You can also buy also specialist geotextile puncture resistant underlays for extra protection.  If you do find a tear, there are repair kits available to patch it up.

So, you can see that there a pros and cons to each option. Preformed ponds are easier to install and durable. Liners take a little more work, but they allow more creative freedom, better planting areas and the option to expand in the future.