To protect your flexible lake liner, it's essential to use a puncture-resistant underlay. At Healthy Lake, we exclusively offer Bonar Yarns UHD Underlay, a premium-grade material with a minimum density of 250 g/m². Lower grade underlays are not a wise long-term investment, as they provide inadequate protection for your pond liner.

The UHD Underlay should be installed on the base and sides of the newly constructed lake before fitting the liner. For particularly flinty or rocky soil, we recommend removing any sharp stones and covering the lake base with 2 inches of sand before laying the underlay.

To calculate how much underlay you’ll need, match the same square meterage as your pond liner. For example, if your liner measures 30m x 30m (total 900m2), then make up 900m2 of underlay (or the closest square meterage possible) with the available sizes on the drop-down tool.