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How to Choose the Right Pond Liner

When you’ve decided to put in a pond liner there are a couple of things to consider, how big does it need to be and what material is right for me?

How big does your liner need to be?

To work this out, you’ll need to measure the hole you’ve dug. You’ll need the maximum length, maximum width and maximum depth. If your pond is rectangular, this is easy, but if it is an odd shape then imagine a rectangle has been drawn around the shape that the whole pond would fit inside.

Calculate what size liner you’ll need by measuring the following:

Length + (2 x depth) + 1 metre (for overlap) = the length of pond liner you’ll need

Width + (2 x depth) + 1 metre (for overlap) = the width of pond liner you’ll need


4 metre long and 3 metre wide pond that’s 1 metre deep

Length     4 + (2 x 1) + 1 = 7m

Width     3 + (2 x 1) + 1 = 6m

So you’d need a pond liner that’s 7m x 6m. If you get stuck a great online calculator can be found here.

What type of Liner?

Pond liners come in a variety of materials and costs. It’s worth mentioning that while some pond liners will stretch, they shouldn’t be stretched to fit the pond or fold them into the corners. Lighter weight pond liners are easier for complicated shapes.

Starting with the most expensive….


This is a branded type of rubber liner. It is very puncture-resistant, heavy and lasts a long time. It can also stretch quite a bit and returns to shape. This is a great choice if your pond might have things dropped in it (i.e. front garden?), or if you have dogs that might jump in and scrabble out. Butyl is also suitable for those who want to build on top of the liner e.g. coping stones or other work. You don’t want to have to re-do this if the liner fails. Butyl usually comes with a 30-year guarantee.


This is a similar material to Butyl and has the same puncture resistance and stretching quality. It is heavy too, but usually a little cheaper than Butyl. Brands include Firestone, SealEco or Greenseal. EPDM often comes with a 30-year guarantee.


Probably the most widely used pond liner, PVC is lighter and less puncture resistant than the rubber ones, but it is also cheaper. It can stretch, but won’t return to shape. PVC liners come with guarantees ranging from 10 to 30 years.


This is the best value liner and is easier to handle and fold into shape than the rubber liners. It is very strong, but is less puncture resistant than Butyl. Polyex comes with a 25-year or lifetime guarantee.


Most pond liner guarantees are invalid unless you use an aquatic brand underlay. These are made of non-woven textile materials and can stop roots and small stones from penetrating the liner. They don’t rot and so stay in place as long as the liner.

Often they come in two weights. Thinner ones, like Permalay, are great for ordinary ponds while thicker heavy-weight ones, like Polyfibrelay, are better for when there are significant tree roots or stony ground in the hole.

People often use old carpets or newspapers as underlay, but as these rot down, the protection they offer will reduce and a stone that was previously covered might pierce the liner in a few years.

Bradshaws Direct

For a full range of pond liners in all sizes contact Bradshaws Direct. Their expert advisers can help with all your planning questions. Just call 01904 691169.