Preformed pond or liner: which one should you choose for your project?

“I want to create my first pond: should I choose a preformed pond or a liner?” This is one of the first questions we are asked, both in-store and by email. And the answer depends less on personal preference than on the size, depth, and fish you are considering.

Here is a practical comparison to help you make the right choice from the outset, without regretting it a few seasons later.

The preformed pond: simple and quick

Rigid polyethylene (PE) or polyester shell, supplied with its planting shelves already moulded in. Dig, install, fill.

— Its advantages

• Quick installation, often in a single weekend.
• No liner calculations or folds.
• Built-in planting shelves.
• Durable: no risk of being punctured by a root.

— Its limitations

• Limited volume: most models hold between 200 and 1,000 litres.
• Limited depth: often 45 to 60 cm, sometimes a little more. Below approximately 60 to 80 cm, the water freezes more deeply and warms up quickly in summer.
• Fixed shape.
• Demanding installation: the shell must be perfectly level and supported across its entire surface, otherwise it may warp or crack once filled.

The liner pond: freedom and flexibility

An EPDM liner laid on felt allows you to create any shape, any size, any depth.

— Its advantages

• No size limit, from a 2 m³ pond to a swimming pond.
• Depth of your choice, ideal for overwintering fish.
• Free-form shape and natural banks.
• Lower cost per litre once the pond exceeds a few cubic metres.

— Its limitations

• More preparation: precise earthworks, felt, size calculation.
• Vulnerable to punctures if the base is poorly prepared.
• Folds to manage in the corners.

Also read

To also compare them with polyester ponds, read Liner or polyester for my garden pond?.

READ THE ARTICLE

The comparison

How to properly install a preformed pond

1. Place the shell on the ground and trace its outline, then dig 10 cm wider and deeper.
2. Reproduce the tiers in the soil.
3. Lay a 5 to 10 cm bed of sand at the bottom and compact it.
4. Place the shell and check the level in both directions.
5. Fill with water in 10 cm increments, while simultaneously filling the space around it with damp sand, so that the pressure is balanced on both sides.
6. Check the level at every step.

Our advice for choosing

• You want a decorative water feature, a few plants, or a small fountain: choose a preformed pond.
• You want fish to spend the winter outdoors: choose a liner pond with at least 80 cm of depth in one area.
• Unsure about the size: choose the larger option. Almost all pond owners tell us they wish they had chosen a larger pond.

Frequently asked questions

— Can a preformed pond be installed above ground?

Only models designed for this purpose. A preformed pond intended to be buried is not designed to withstand water pressure without lateral support.

— Can a preformed pond be enlarged?

Not really. You will need to replace it with a liner pond. That is why it is better to think carefully about the size from the outset.

— Can fish survive the winter in a preformed pond?

In a small, shallow preformed pond, harsh winters can be risky. Plan a backup solution (a frost-free container) or choose a deeper pond.

In summary

• Preformed pond: quick and simple, for small decorative ponds.
• Pond liner: flexible and deep, for fish and more ambitious projects.
• When in doubt, choose the larger option.

Still hesitating? Come and see our display ponds at Aquiflor in Nodebais, about twenty kilometers from Brussels.

Last updated: September 27, 2026.