A Guide to Flexible vs Preformed Pond Liners

Pond liners help to ensure that the water in a pond does not leak into the ground, thus eliminating the problem of having to refill it every so often. A pond liner doesn’t just act as a seal, but it also has other important functions that should not be overlooked. Ponds that have been lined have very little chance of getting contaminated as the liner will act as a complete barrier between the water and soil beneath and walls of the pond. Pond liners also help to prevent erosion especially around the pond’s edges when it rains. This way the pond’s shape remains intact and the life inside of the pond also remains undisturbed.

There are two major types of pond liners which are popular with pond owners. These are the flexible pond liners and the preformed pond liners. Each of these two types of pond liners has their own pros and cons which we are going to discuss below:

Flexible pond liners

Just like their name suggests, flexible pond liners are highly flexible and will easily fit into a dugout pond without hassle. They come in a variety of sizes, and as pond owner it will be up to you to choose the one that will best suit your needs. Flexible pond liners usually come as simple pre-cut sheets. Your work as the pond owner will just be to line your pond with it.

Advantages of flexible pond liners

  • Flexible pond liners can easily be molded to conform to the shape of the already dugout pond. Preformed pond liners on the other hand come with a fixed shape and cannot be made to conform to the shape of any pond.
  • Flexible pond liners are usually lightweight and mobile, meaning they can be moved from one point to the next easily. Preformed pond liners on the other hand are heavy and have a definite shape making their transportation to the site of the pond a little cumbersome.
  • Flexible pond liners can easily be customized to meet the needs of a pond owner, while this may not be the case with preformed pond liners. Preformed pond liners have a definite shape because they are usually manufactured at the factory and end up in the hands of the pond owners with an unchangeable formed shape.
  • Certain materials used in the manufacture of flexible pond liners such as butyl, PVC, and LDPE are a good choice because they are inert, meaning they don’t react with the water thus aquatic life in the pond remains safe.

Disadvantages of flexible pond liners

  • Good materials used in the manufacture of flexible pond liners such as butyl and PVC are not so easy to find.
  • The fact that PVC and butyl are not easily available yet they are the best materials used to make flexible pond liners makes the cost of liners made from them rather expensive.
  • Prone to being pierce or punctured, causing leakage.

Preformed pond liners

Preformed pond liners come from the factory with an already determined shape, meaning that the shape is definite. You will not be able to change the shape of preformed pond liner on the site of your pond. However, there are some pond owners who prefer preformed pond liners for the benefits that they offer to them. Lets us now look into the benefits of using preformed pond liners:

Advantages of preformed pond liners

  • Preformed pond liners once installed, will not show any pleats or folds on corners of the pond because it has a definite shape that will not fold. Flexible pond liners have a tendency of bunching up on the corners of the pond, and technicians usually have to fold them in order for the lined pond to look neat.
  • Preformed pond liners made of fiber glass are very rigid and can be placed above ground and have water poured into it without any worries. This can later be followed later with landscaping after which it can then be covered with soil. Preformed pond liners made of plastic however have to be put right away into the pond to avoid any chance of it from breaking.
  • A preformed pond liner is easy to install because once you have the dimensions of the dugout pond and that of the liner you simply just place it into the space.
  • The plastic material used to make most of these preformed pond liners is readily available making them rather affordable.

Disadvantages of preformed pond liners

  • The major disadvantage of preformed pond liners is their predetermined shapes make pond owners first to have to make ponds that have the dimensions similar to them. What this means is that you cannot change the shape, design, and look of your pond once the liner is installed.
  • With their definite shape and size, carrying them around during installation may be a difficult task.
  • Most preformed pond liners found available are often too shallow ,meaning that regulating water temperature for the fish will not be optimal and this may cause problems for the fish inside of the pond.
  • Preformed pond liners made of fiberglass, though strong and long lasting ,are usually too heavy and large making their transportation quite expensive and cumbersome.


Both flexible and preformed pond liners have their own benefits and drawbacks, so the final decision on the kind of pond liner to use remains solely the discretion of the pond owner. You can proceed to choose any pond liner that you feel will best meet your very own unique needs.