Reversible Black/Brown Pond Liner with Underlay | Lifetime Guarantee | Fish Safe
Building a garden or wildlife pond and want it to look right once the water goes in? This reversible pond liner is black on one face and brown on the other, so you choose the finish as you lay it: brown side up for an earthy, natural pond floor, or black side up for deep, mirror-like water. Every liner comes with a protective underlay and a lifetime guarantee for below-ground ponds, in 86 sizes from 2m x 2m to 50m x 10m.
Why it works
A woven core between two laminates
A woven polyethylene core carries the strength, laminated between two smooth, UV-stabilised outer layers that hold the water and give algae little to grip. Because the core takes the load, the sheet is very hard to tear even once cut.
Two finishes from one sheet
Both faces are coated and UV stabilised, so neither side is a "back". Brown disappears under silt and planting; black makes the water look deeper and fish colours stand out.
Light enough to lay yourself
At 0.35mm it is the lightest liner in our range, so one or two people can carry, unfold and position a garden-pond size without lifting gear.
- Reversible black/brown finish
- Woven core resists tearing
- UV stabilised on both sides
- Underlay included
Where it's used
Wildlife ponds and bog gardens with a pebble beach, brown side up. Formal patio ponds and reflecting pools set into the ground, black side up. First-time DIY ponds, larger landscape ponds, and rills or streams using the 10m x 1m and 10m x 2m strips.
Specifications
| Property |
Specification |
| Material |
Polyethylene: woven core laminated between two outer layers |
| Thickness |
0.35mm |
| Colour |
Reversible: black one side, brown the other |
| UV resistance |
UV stabilised on both sides |
| Rot resistance |
Rot-resistant coating on each side |
| Fish safe |
✅ Yes — certified safe for all aquatic life |
| Stretch |
None: fold into corners |
| Underlay |
Included; weight not published for this line |
| Guarantee |
Lifetime: manufacturing faults including seams, below-ground ponds |
| Repairs |
Double-sided liner tape; liquid sealants do not bond |
| Sizes |
86, from 2m x 2m to 50m x 10m |
Choosing the right size and side
Liner length = pond length + (2 x maximum depth) + 0.6m
Liner width = pond width + (2 x maximum depth) + 0.6m
The 0.6m leaves a 30cm overlap on every edge. Round up to the next size; sizes work either way round. A 3m x 2m pond 0.6m deep needs 4.8m x 3.8m, so order 5m x 4m; a 4m x 2.5m pond 0.8m deep needs 6.2m x 4.7m, so order 7m x 5m. The pond liner size calculator does it for you.
Pick the side before you fill: brown for wildlife and planted ponds where the liner should vanish, black for formal shapes and fish ponds where you want reflections.
This liner is for ponds dug into the ground. It has no stretch and is less puncture resistant than rubber, so for raised ponds, or koi ponds deeper than 1.2m, choose EPDM rubber; for large regular ponds see HDPE.
Installation, use and care
- Remove sharp stones and roots and add 50mm of soft sand to the base.
- Lay the underlay over the whole hole, overlapping joins by 300mm.
- Warm the liner in the sun and unfold it centrally, chosen colour up.
- Fold, don't stretch, at corners; fill slowly, easing out creases.
- Trim to about 300mm and bury the edge under turf, paving or stone.
Punctures can be repaired with a double-sided liner tape patch on a clean, dry surface.
Frequently asked questions
Is underlay included with this pond liner?
Yes. A protective underlay comes with every liner at no extra cost. Lay it over the prepared, stone-free base first, then lay the liner on top, so stones and roots cannot push up into the liner.
Which side of the liner should face up?
Either. Brown side up gives a natural, earthy look for wildlife and planted ponds; black side up gives a reflective look for formal ponds. Both sides are UV stabilised, so the choice is purely about appearance.
How thick is it, and is it strong enough?
It is 0.35mm thick. Its strength comes from the woven core laminated inside the sheet, which makes it very hard to tear. It has no stretch, so lay it on a smooth base with the underlay and fold it into corners.
Can I use it for a raised pond?
We don't recommend it. It performs best in ponds dug into the ground, and the lifetime guarantee applies to below-ground installation. For raised ponds choose an EPDM rubber liner, which copes better with the water pressure on the walls.
What size liner do I need for a 3m x 2m pond?
For a 3m x 2m pond that is 0.6m deep you need at least 4.8m x 3.8m of liner, so order the 5m x 4m size. The formula is pond length (or width) + (2 x maximum depth) + 0.6m.
Ordering and delivery
The price shown includes the liner and underlay. The largest sizes travel on a pallet, so make sure someone can accept delivery and tell us about access restrictions when you order. Liners are cut to size and can't be returned, so check your measurements first.
✅ Trust & Guarantee
- ✅ Fish Safe Certified — Safe for all fish species and pond wildlife
- ✅ Free UK Delivery — All mainland UK orders delivered free
- ✅ Lifetime Guarantee — Premium lifetime material warranty
- ✅ Expert Advice Available — Our team can help you choose the right side and size
Helpful guides
