Industrial-Grade 0.35mm HDPE Pond Liner – 25-Year Guarantee | UV-Resistant, Tear-Proof, Waterproof Sheet

Black 0.35mm HDPE pond liner for garden, koi and wildlife ponds

You have a hole to line, or a pond that has started to lose water, and you need a sheet that fits first time. This black 0.35mm HDPE pond liner is sold in 51 pre-cut sizes, from 2.5m x 2.5m up to 30m x 40m, so it suits a small wildlife pond in a back garden as readily as a landscaper's large ornamental pond. Use the size guide below to work out what you need, then pick the next size up.

• Material: black HDPE, 0.35mm thick, made from 100% virgin material
• Guarantee: 25 years against UV damage from sunlight
• Handling: very supple, with no stretch, so it folds into shape
• Underlay: not included, and we strongly recommend using it
• Delivery: Express UK Delivery, large sizes may arrive on a pallet

Create a Long-Lasting Pond with Industrial Strength

When building a garden pond, the liner is your most crucial investment. Our 0.35mm thick Industrial-Grade HDPE Pond Liner is engineered to provide lasting performance, offering a 25-year guarantee for worry-free installation and use.

Key Benefits

• Heavy-Duty Durability – Made from high-density polyethylene (HDPE) for maximum resistance to punctures, tears, and pressure from soil or water weight
• UV-Resistant – Designed to withstand prolonged sun exposure without degrading, cracking, or weakening over time
• Flexible Fit – Easily adapts to any pond shape or contour, ideal for custom water features, koi ponds, or wildlife habitats
• 25-Year Manufacturer Guarantee – Peace of mind with a long-term performance promise
• Eco-Friendly Material – Recyclable and safe for aquatic life, with no leaching or chemical contamination

What that means on site

HDPE stays supple without stretching, and that changes how you fit it. A rubber liner pulls tight into a corner, whereas this one lies loose and takes up the shape in folds. You get a lighter sheet that is easy to carry and unfold, but the size has to be right before you start, because the sheet will not give you extra length. Allow for every side, and take your measurement over any shelves and contours rather than straight across the top.

Black is also the practical colour for a pond. It hides the base once the water has settled, which gives planting and fish a natural, deep-looking background.

Which size pond liner do I need?

Measure the longest and widest points of the pond and its deepest point, then use this sum for each direction:

Liner length = pond length + (2 x depth) + (2 x 0.5m edge)
Liner width = pond width + (2 x depth) + (2 x 0.5m edge)

Dig the pond first and measure the hole, not the plan. For an irregular shape, run a tape down one side, across the base and up the other, following the contours, then add the edge allowance. These examples use the sizes we list:

If you fall between two sizes, take the larger one. You can trim spare liner once the pond is full, but you cannot add to a sheet that falls short.

Ideal For

• Garden fish ponds
• Koi ponds
• Wildlife habitats
• Decorative and ornamental water features
• Multi-tiered or irregular pond layouts

The larger sizes suit landscaping contractors lining ornamental ponds in commercial grounds. The long 10m x 1m and 10m x 2m sheets suit streams and narrow rills, where one continuous piece avoids a join in the channel.

Choosing the right liner

Underlay is the first decision. This listing is the liner alone, which makes sense if you already have underlay or are lining a smooth, stone-free base. If you need both, the listings below come with underlay, so you can buy everything in one order. Compare them on guarantee and on what is in the box:

Stay with this liner when the budget matters most and your ground is well prepared. Move up if the site is stony or full of roots, or if you plan to fit a koi viewing window, because this liner is not suitable for one.

Why Choose HDPE Over Traditional Rubber Liners?

HDPE liners outperform traditional rubber in both puncture resistance and UV durability. They require less maintenance, hold their shape longer, and offer a better return on investment thanks to their extended lifespan.

Technical Specs

Environmentally Responsible Choice

Our HDPE pond liners are non-toxic, chemically inert, and safe for fish, aquatic plants, and surrounding soil. They’re made using recyclable materials, supporting a more sustainable pond ecosystem.

Installation, use and care

1. Dig and prepare. Cut the shape with any planting shelves, check the rim is level all the way round, then remove stones, roots and anything sharp.
2. Lay the underlay. Cover the base and sides. Underlay cushions the liner and is your main protection against punctures, which the guarantee does not cover.
3. Unfold the liner. A warm day makes the sheet easier to handle. Centre it over the hole and let it lie loose. Larger sizes need two or more people.
4. Fill slowly. Add a little water so its weight draws the sheet down, then smooth the sides and form neat folds at the corners as the level rises. Hold the overlap with smooth stones, not sharp ones.
5. Finish the edge. Once the pond is full, trim the excess, leaving at least 0.3m. Bury it in a trench or cover it with coping so soil cannot wick water out of the pond and the sun stays off the liner.

If you are using tap water with fish, treat it with a pond dechlorinator first. After that, the liner only needs a check for damage when you clean the pond out. Avoid sharp tools and spiky plant roots near it.

Frequently asked questions

Does this pond liner come with underlay?

No. This listing is the liner only. We strongly recommend underlay beneath it, since it protects against stones and roots. If you want underlay in the same order, choose our 40-year or lifetime-guarantee HDPE liner, which both include it.

What does the 25-year guarantee cover?

It covers UV damage caused by sunlight. It does not cover punctures, so prepare the ground well and use underlay. Keep your order confirmation as proof of purchase, and call us on 01744 520 110 if you have a question about a claim.

Is 0.35mm thick enough for my pond?

For garden, koi and wildlife ponds on properly prepared ground with underlay, yes, this is the thickness it is made for. It is thinner than most rubber liners, so on very stony or root-filled ground it is worth moving up to a liner sold with heavy-duty underlay.

Can I use it for a koi pond?

Yes, it is suitable for koi ponds, and the material is safe for fish. The exception is a pond with a viewing window, because this liner cannot be used with a koi window.

How will a large liner be delivered?

Orders placed before 2pm, Monday to Friday, are dispatched the same day by Express UK Delivery. Larger sizes may come on a pallet to protect them in transit, so make sure there is clear access and someone available to help move it.

Conclusion

The Industrial HDPE Pond Liner is the ideal solution for homeowners, landscapers, and pond builders looking for reliable performance and long-term durability. Whether you're designing a peaceful backyard retreat or a high-functioning koi pond, this liner ensures water stays where it belongs—for decades.