Guide

How to install a box welded pond liner

Installation is the easy part. Here's how to prepare the site, position the liner and get the best possible result.

Before the liner arrives

Ensure the pond excavation is complete, smooth and free from sharp stones, roots or debris. Fit a geotextile underlay — this protects the liner from below and is strongly recommended for all pond types. For raised ponds, ensure the walls are structurally complete.

Installation steps

  1. 1Unfold the linerCarefully unfold the liner on a clean surface next to the pond. Take care not to drag it across rough ground.
  2. 2Lower it inWith a helper, lower the liner into the pond. The box-welded shape means it will naturally orientate itself correctly. There is no folding or pleating required.
  3. 3Seat the basePress the liner gently into the base, ensuring it lies flat against the underlay. Work from the centre outwards to avoid trapping air underneath.
  4. 4Position the wallsAllow the liner walls to fall naturally against the pond walls. For a box-welded liner, this requires no adjustment — the liner is already the right shape.
  5. 5Fill slowlyBegin filling. The weight of water will settle the liner firmly against the walls. Check regularly that the liner is sitting correctly as the water level rises.
  6. 6Secure the lipFold the lip allowance over the top edge of the pond. Hold in place temporarily with edging stones while you complete the coping detail.

Frequently asked questions

For a small garden pond, two people is sufficient. For larger ponds, three or four is recommended — the liner is bulky when folded and easier to position with extra pairs of hands.

No. Box-welded liners are designed to be fitted by a competent DIYer or landscaper. The installation is significantly simpler than flat sheet because there is no folding required.

The liner is manufactured to your exact dimensions, so trimming should not be necessary. If the lip allowance is more than needed, fold the excess under the coping rather than cutting it.

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