Geosynthetic Clay Liner (GCL) Pond Construction in Devon & Cornwall
Natural, Plastic-Free Pond Liners for Lasting, Eco-Friendly Water Features
At Sasaquatics Ltd, we specialise in the design and construction of ponds and wetlands lined with Geosynthetic Clay Liners (GCLs) — a modern, environmentally responsible alternative to traditional plastic pond liners.
Whether you’re creating a wildlife pond, or agricultural waterbody, GCLs offer a long-lasting, low-impact solution perfectly suited to Devon and Cornwall’s varied soils and rainfall patterns.
What Is a Geosynthetic Clay Liner?
A Geosynthetic Clay Liner (GCL) is a natural waterproofing membrane made from sodium bentonite clay sandwiched between two layers of geotextile.
When hydrated, the clay swells and forms a dense, self-sealing barrier — preventing water loss while allowing the pond to remain fully natural and free from synthetic plastics.
Key benefits include:
- 100% natural and plastic-free waterproofing
- Self-healing capability if punctured
- Durable and resistant to root penetration
- Ideal for wildlife ponds, wetlands, and rewilding projects
- Simple to install and conformable to natural contours
Why Choose GCL for Natural Ponds?
Devon and Cornwall’s mixed soils and rocky sub-layers can make traditional liners difficult to install or secure. A GCL adapts to the ground naturally, forming a robust seal even on sloped or irregular terrain.
It’s also an excellent choice if you’re seeking a sustainable, low-visibility liner that blends seamlessly with natural materials like clay, gravel, and aquatic planting.
At Sasaquatics, we often recommend GCLs for:
- Wildlife and rewilding ponds
- Natural swimming ponds and garden pools
- Farm irrigation or livestock ponds
- Wetland scrapes and habitat creation projects
- Landscape-scale rewilding and water retention features
Our GCL Pond Construction Process
Every Sasaquatics project is fully tailored to your site and goals:
- Site Assessment & Design
- We survey gradients, soils, and hydrology using contour data and DEFRA mapping tools.
- Designs are created to maximise water retention and ecological value.
- Excavation & Profiling
- Shaping is carried out by skilled operators to achieve smooth contours and shallow wildlife margins.
- Subgrade Preparation
- The pond base is cleared of sharp stones and levelled to create a stable foundation.
- GCL Installation
- The clay liner is laid in overlapping panels, secured, and hydrated for an immediate watertight seal.
- Edge Protection & Covering
- Natural soils, gravel, and planting media are added to protect the liner and blend the pond into its surroundings.
- Planting & Finishing
- We establish native aquatic plants and marginal zones for biodiversity, clarity, and long-term stability.
Eco-Friendly and Wildlife-Safe
Because GCLs are free from plastics and synthetic membranes, they integrate naturally into the environment.
They are safe for amphibians, birds, and aquatic invertebrates, and they don’t leach chemicals into the water.
This makes them the perfect choice for:
- Rewilding projects
- Biodiversity net gain sites
- Natural swimming ponds
- Ecological restoration schemes
Why Choose Sasaquatics Ltd?
Based near Moretonhampstead, Devon, we combine ecological expertise with hands-on construction experience — delivering complete, wildlife-friendly water systems.
Our clients include:
- Private landowners and estates
- Farmers and smallholders
- Rewilding projects and nature recovery initiatives
- Local authorities and community groups
We also offer:
- Full hydrology and pond design plans
- Planting schemes and ecological aftercare
- Assistance with grant and ELMS funding applications
Serving Devon, Cornwall & the South West
We design and build GCL-lined ponds across:
Devon, Cornwall, Somerset, Dorset, and South Hams, with projects completed from the Tamar Valley to the South Hams coast.
Our team understands local soil types, rainfall conditions, and wildlife priorities — ensuring every pond is built to last and thrive.
Get a Quote or Site Visit
If you’re considering a natural, plastic-free pond liner for your property, we’d love to help.
We can arrange a site visit and feasibility check anywhere in Devon or Cornwall.
📞 Call: [Your phone number]
📧 Email: [Your email address]
What is a Geosynthetic Clay Liner (GCL)?
A Geosynthetic Clay Liner (GCL) is a natural waterproofing membrane made of sodium bentonite clay sandwiched between two layers of geotextile fabric.
When hydrated, the clay swells and forms a dense, self-sealing barrier that prevents water loss — offering a natural, plastic-free alternative to PVC or EPDM liners.
Are GCL ponds environmentally friendly?
Yes. GCLs are 100% natural and plastic-free, containing only bentonite clay and textile layers. They don’t release chemicals into the water and are completely safe for fish, amphibians, plants, and wildlife. They are a great choice for rewilding projects, natural swimming ponds, and biodiversity enhancement schemes.
How long does a Geosynthetic Clay Liner last?
When properly installed and covered, a GCL can last well over 50 years.
Because the bentonite clay self-heals if punctured, it remains watertight and low maintenance for decades — making it one of the most durable natural lining options available.
Can a GCL be used for all pond types?
Yes. Geosynthetic Clay Liners are suitable for:
Wildlife and rewilding ponds
Natural swimming ponds and ornamental water features
Farm irrigation or stock ponds
Wetland scrapes and ecological habitats
They can be shaped to fit almost any form, slope, or gradient.
Do I still need to cover a GCL liner?
Yes — all GCLs should be covered with soil, once installed.
This protects the liner from drying out, UV light, and physical disturbance, and allows for natural planting and wildlife colonisation.
Is a GCL better than a plastic pond liner?
For many natural and rewilding ponds, yes.
GCLs are more sustainable, self-healing, and blend better with natural landscapes than synthetic liners. They’re particularly effective in Devon and Cornwall, where rocky soils or uneven bases make flexible plastic liners harder to secure.
Do Geosynthetic Clay Liners work in clay or rocky soils?
Yes — GCLs are often used to reinforce existing clay soils or seal areas with shallow bedrock. They conform closely to ground contours and seal small cracks or voids that might otherwise leak. They should not be laid on sharp stones so sometimes fine soil or sane needs applying.
How much does a GCL pond cost?
Prices vary depending on size, depth, and site access.
As a guide, small wildlife ponds start around £6,000–£8,000, while larger lined ponds for habitat or swimming can range from £12,000–£25,000+ including design, excavation, and planting.
Do you handle design and installation?
Yes — Sasaquatics Ltd offers a complete design-and-build service across Devon and Cornwall, including:
Site surveys and hydrology design
Liner supply and installation
Planting, filtration, and ecological finishing
Long-term maintenance and water quality checks
We also assist with grant applications under ELMS, Local Nature Recovery, and biodiversity funding schemes.
Will my pond qualify for funding or grants?
In many cases, yes.
Wildlife ponds, wetlands, and water-retention features lined with natural materials like GCLs often qualify for ELMS (Environmental Land Management Scheme) or local Nature Recovery grants.
We can help identify relevant funding streams and support your application.
