The Most Comprehensive Guide to Pond Liners

The Most Comprehensive Guide to Pond Liners

January 30, 2023

When your home DIY or commercial pond or water feature project exceeds the realms of pre-formed poly pond liners then it’s time to start designing and building with flexible pond liner. These liners allow you to create ponds and water features of virtually any shape and on any scale. The only real restriction is your imagination! Here’s our guide to flexible pond liners in Australia.

Advantages of flexible liner. 

The primary advantage of flexible liners is their versatility. They allow construction, on virtually any scale, of water features and ponds of every shape and style a design concept calls for. You may need:

  • a long rill or natural-look creek running into a pond
  • a stock dam where rammed earth does not seal adequately
  • a meandering string of water hazards on a golf course 
  • a home garden pond that needs to fit a specific shape

All of this can be easily achieved using flexible pond liner.


Flexible pond liner varies in thickness with the type used. They range from 0.5mm to 1.2mm thick for high-strength commercial applications. Their flexibility is part of their secret for resisting damage and punctures – they tend to flex and mould around anything which may otherwise cause damage. This same flex also helps to prevent stress tears.

Of course, it is important to ensure the risk of punctures is avoided by appropriately preparing the substrate bed on the liner that will be laid. Should damage occur then it can be easily and reliably repaired using a suitable repair kit or jointing tape.

Flexible liners also have a very long lifespan. You’ll find PVC liners carry a 10-year UV warranty and EPDM liners carry 20-years. Now bear in mind, this is only the UV warranty period. There are real-world examples of flexible liners still performing well in the landscape after more than 40-years!

Preparation work

Probably the greatest misconception is around the amount of substrate preparatory work required for flexible liners. 

A typical instal simply involves excavation to form. If the soil is free from potentially damaging material, such as rocks and roots, then the flexible liner can be laid directly onto this base.

If the soil contains puncture risks that cannot be easily or economically cleared then the excavation is increased in size by as much as is required to allow for a safe bed to be formed. This bed will usually be a damp river sand or similar which can be easily moulded to shape.

In some instances, you may find that such extra preparation is only required in one part of the excavation. It will always vary with the site and the project.

Types of flexible liner

When you look at flexible liners you’ll find two main types are available PVC and EPDM.

  1. PVC – Cost effective and reliable, PVC liners are a great entry-level choice for simple pond creation. Most landscape specialists will tell you that PVC is suitable for ponds of up to 5000L in volume however this will vary with water depth and design. PVC has only a small amount of flex, and stretchiness, as it’s a plastic product so isn’t the best choice for ponds with convoluted beds. It’s quite durable but not recommended for situations where people or animals may be accessing the pond. As it has a lower degree of flex it is not a good choice where large landscape rocks will be positioned in the pond or around its edge or for underlay on cascades and waterfalls where large rocks will be used.
  2. EPDM -
    Extremely durable and flexible EPDM is in fact a synthetic rubber. This is where its stretch comes from. It can stretch to around three times its actual size so can mould around all manner of irregular shapes. This also means it is ideal for using beneath large landscape rocks, cascades and the like. It’s the preferred material for ‘swim’ ponds as it has no problem with foot traffic. This same stretch also makes it much more resistant to punctures and stress tears. It’s considered as the better choice for ponds containing fish and plants too.

Rolls or packs? 

Both PVC and EPDM liners are available from the roll, when longer lengths are required, or in pre-cut flat packs. 

For larger projects buying from the roll will generally be more economical as you’ll reduce wastage, only buying as much as you need. It also has an advantage in installation as less joins are required meaning your project can run faster.


The sheet thickness of flexible liner is an indicator of durability. PVC tends to only be available in 0.5mm whereas EPDM is available in a number of thicknesses;

  • Firestone PondEasy liner is 0.8mm thick offering an excellent level of durability for most projects.
  • Firestone GeoSmart liner is 1.2mm thick offering unparalleled commercial-grade durability for projects of any scale.

As you would anticipate, the thicker liner will be more expensive.

Creating larger sheets. 

Pre-packed sheets and liner from the roll will give you the size to cover the bulk of your projects, there will always however be situations where much larger sheets are required. The solution to this is simple joining tapes. When a specific tape exists for your liner type it is good practice to use it although there are tapes that can be used on both PVC and EPDM.
It is critical for creating a quality join that instructions for use be followed very carefully as some do recommend using specialised primers before applying tape.

The professional solution 

If you have a project in the pipeline, large or small, and want to take it to the next level of quality and professionalism then it’s time you switched to using a flexible pond liner. Cost effective, durable, long lasting and easy to install. Pond liner are the ultimate solution for ponds and water features.


Browse PondMAX’s extensive range of outdoor pond products online now, or get in touch today with any queries.