UV-armoured surface
Stabilised against direct sunlight — no brittling, no bleaching, no annual checks.
Reinforced pond liners
Reinforced pond liners — RPM 0.7 mm, heavy-duty for any UK pond
Reinforced pond liners in 0.7 mm RPM: a UV-stabilised polyolefin membrane with a woven polyester scrim. The honest upgrade from EPDM rubber pond liners — fish-safe, on-site weldable and scaled for large UK ponds and lined reservoirs.
What you're buying
The reinforced pond liner pros actually specify
A reinforced pond liner is a flexible waterproof membrane built around a woven polyester scrim that is laminated between two polymer skins. The scrim is what carries the load — it stops the sheet stretching, tearing at the shelves, or being punctured by stones and roots underfoot. That is why a 0.7 mm reinforced liner consistently outperforms a 1.0 mm or even 1.5 mm unreinforced sheet in real installations.
Our RPM 0.7 mm is the version most UK pond builders and aquatics contractors specify today. It is roughly half the weight of EPDM at the same span, so two people can handle a 6 × 4 m liner without machinery. It is thermoplastic, so seams are welded — not glued — and stay watertight for the life of the pond. The top layer is UV-stabilised, so it does not need an annual check or a shade cover, and the formulation is plasticiser-free and certified for potable water contact, which means it is safe for koi, native fish, amphibians and aquatic plants from the moment the pond cycles.
Whether you're lining a wildlife pond, a formal koi pond or a small reservoir, the spec below is the same liner — one grade, properly engineered, backed by a 45-year lifespan. The same RPM membrane is specified at scale across agricultural slurry and irrigation lagoons, golf-course water hazards and fishing and ornamental lakes — see the full pond liner applications hub for details.
The heavy duty pond liner option
When people search for a heavy duty pond liner, they're almost always describing what reinforced RPM already is: a puncture-resistant woven scrim laminated between two polymer skins, finished at 0.7 mm total thickness. The scrim is the heavy-duty bit — it stops the sheet stretching at the shelves, resists roots and sharp stones from below, and lets the liner take real installation abuse without tearing.
The other thing worth knowing is that heavy duty pond liners don't have to be heavy. A 0.7 mm reinforced sheet matches (and usually beats) the puncture rating of 1.0–1.5 mm EPDM, at roughly half the weight per square metre. That's the difference between a two-person weekend install and needing a third pair of hands just to unfold the sheet — same strength, far less mass to move around the garden.
0.7 mm
Reinforced polymer
Built for longevity
Engineered to outlast the garden around it.
We make one thing, and we make it properly: a 0.7 mm reinforced polymer membrane (RPM) with a UV-stabilised top layer. No upsells, no choosing the wrong grade — just the liner pond builders specify.
Reinforced 0.7 mm core
Polyester scrim woven through the polymer for tear, puncture and root resistance.
Aquatic-life safe
Inert, plasticiser-free formulation. Safe for fish, frogs, plants and wildlife.
−30 °C to +70 °C
Stays flexible through frost and heat — ideal for unpredictable British weather.
Easy to fit
Light, drapeable and weldable on site. Half the weight of EPDM at the same span.
Recyclable polymer
Single-material construction — fully recyclable at end-of-life. No PVC plasticisers.
Technical specifications
Full RPM pond liner spec sheet
Manufactured in Germany to EN ISO standards. Every roll ships with batch traceability.
| Base cloth | Polyester |
|---|---|
| Coating | Flexible PVC both sides |
| Finish | Matt |
| Total weight | 610 gsm |
| Roll sizes (nominal) | 150 cm, 205 cm, 250 cm, 300 cm, 320 cm × 50 m |
| Tensile strength | Warp 2,500 N / 50 mm · Weft 2,500 N / 50 mm (EN ISO 1421) |
| Tear strength | Warp 300 N · Weft 280 N (DIN 53363) |
| Coating adhesion | 80 N / 50 mm (DIN 53357) |
| Fire behaviour | < 100 mm/min — Pass (ISO 3795 / FMVSS 302) |
45-year lifespan
RPM is engineered for a 45-year service life under normal pond use, resisting UV degradation, brittling and material failure long after PVC and butyl liners have failed.
- UV-stabilised top layer prevents brittling and cracking
- Welded seams test stronger than the parent sheet
- Field-repairable with a hot-air welded patch
- Real-world UK installs routinely exceed 30–40 years
Underlay guidance
RPM is tough — but every liner lasts longer with the right underlay. A protective layer cushions the membrane against stones, roots and ground movement, and it costs far less than relining a pond.
Standard ponds (≤ 1.5 m deep)
300 g/m² needle-punched geotextile underlay, lapped 100 mm at joins. Suitable for most garden ponds on prepared soil.
Stony, rooty or reclaimed ground
500 g/m² geotextile, with a 50 mm bed of sharp sand below on poor ground. Worth the extra cost — punctures almost always start from beneath.
Large or deep ponds (> 1.5 m, swim ponds, reservoirs)
700 g/m² geotextile, double-layered on shelves and benches. We supply matched underlay rolls cut to your liner spec.
Next steps
Size your liner, compare materials, or get a quote with welds and underlay included.
How RPM compares
How RPM compares to other pond liner materials
Reinforced polymer overlaps with most of the established UK pond liner materials. Each material guide below covers lifespan, fish safety, installation and price for the alternative — and is honest about where RPM wins and where it doesn’t.
EPDM
EPDM rubber vs RPM
Read guideButyl
Butyl rubber vs RPM
Read guidePVC
PVC vs RPM
Read guideHDPE
HDPE vs RPM
Read guideRPE
RPE vs RPM
Read guideFibreglass
Fibreglass vs RPM
Read guideHead-to-head matchups
Direct side-by-side comparisons against the three materials RPM is most often specified instead of.
Product questions
RPM pond liner FAQs
The questions we get most often about the 0.7 mm reinforced polymer membrane.