How to Calculate the Size of Pond Liners


The pond liner is one of the most important parts of a water garden pond because it is used on the inside of a fish pond to retain water and prevent leaking. Pond liners come in several materials and a variety of weights, and are either available pre-cut in standard sizes or from a large roll, much like a carpet roll. Purchase pond liners online or at specialty water garden pond stores as well as at and big box stores selling fish pond supplies. Prices vary along with quality. Follow these basic directions for calculating the size of any pond liner needed for most water garden ponds, pondless waterfalls and pond fountains.


Choosing the Correct Material for a Pond Liner

  • Determine the type of material. There are several products available for pond liners available such as Polyethelyne, Fiberglass, PVC and rubber. Rubber, however, is probably the best product for garden pond liners because it is inexpensive, very flexible, comes in several weights, will not harm fish or plant life and can be used permanently.


Measure the Garden Pond Accurately

  • Measure the length, width and depth of the water garden pond using a tape measure. If the garden pond is irregular in shape measure the longest, widest and deepest parts. Don’t skimp on the measurements because it’s better to have a pond liner that is oversized than one not large enough.


Calculate Pond Liner Size with a Simple Equation

  • Determine the length of a pond liner by adding the length of the water garden pond + twice the depth + 2 extra feet. For example lets say the water garden pond is 6 feet long and 3 feet deep. The length of the pond liner would be 6 + 6+ 2 = 14 feet.
  • The additional length allows for adequate manipulation and placement of the fish pond liner into nooks and crannies of your water garden pond. It allows room for the pond pump as well as rock placement without risking tearing from over-stretching.
  • Determine the pond liner width by adding the width of the water garden pond + twice the depth + 2 extra feet. For example lets say the backyard garden pond is 3 feet wide and 3 feet deep. The length of the pond liner would be 3 + 6+ 2 = 11 feet.
  • Using the above calculations as an example, the appropriate fish pond liner will be at least 14 feet long by 11 feet wide.
  • The added size also offers the option of being able to install the pond liner in one piece, an important facet of building a good, leak-proof garden pond or backyard waterfall. Extra lining material along edges can be folded under, tucked in or trimmed to reduce bulk. The additional size also makes it easier to clean a pond and not risk pulling the liner edges out from under rocks.

Pricing a Pond Liner

  • Check with various stores selling fish pond supplies for the best pricing on pond liners. The larger they liner needed, the more expensive, and some stores are significantly less expensive than others. It may be tempting to choose a garden pond liner made from lighter gauge material to save money, or of an inferior fabric, but beware. When installing a pond liner, it can tear or be punctured by rocks or develop small leaks over time where better quality materials will not. To be safe and ensure the pond liner will last a good long time, choose one that is heavier gauge rubber.


Careful measuring will help to avoid having to use more than one piece of liner and prevent the need for seams and sealants which may leak. Once the pond liner size has been properly calculated, it’s easier to build and maintain a beautiful water garden pond with confidence.

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