How to Choose a Pond Liners

Keep your water garden healthy by installing a liner that won’t break down over time

How to Choose a Pond Liners

Water gardens can be a great addition to your backyard. The key to a successful installation is choosing the right liner. Pond liners are the most versatile way to build a pond, and there are many to choose from based on your climate, budget and chosen location.

Water garden liners are also key to keeping aquatic life healthy. Swimming pool liners or heavy plastic sheeting may break down over time and can be toxic to fish and plants. 

This guide highlights the different types of pond liners, what they’re made of, and measurement considerations.

Types and Materials

There are three main types of pond liners to choose from: flexible, preformed and concrete liners.

Flexible Liners

  • Flexible liners are made of lightweight plastic or rubber that can be cut into any desired shape. They are ideal for oversized or uniquely shaped ponds.
  • There are three general types of flexible liners: ethylene propylene diene monomer (EPDM), polyvinyl chloride (PVC) and butyl rubber. They come in premeasured sheets and rolls in brown, green and black.

Preformed Liners

  • Preformed liners are good for a definite shape and size and are usually constructed of a strong plastic like high-density polyethylene (HDPE) or fiberglass. They range in size from 3 to 6 feet across and 18 inches deep.
  • Because preformed liners tend to be smaller and shallower, be sure to watch for fluctuating water levels and low oxygen levels if you have fish or plants.

Concrete Liners

  • Concrete ponds are made from a mix of cement, sand, gravel and water. Weather is a critical factor as freezing conditions will make the concrete disintegrate before it cures.
  • Concrete ponds require reinforcing mesh, rods or expansion joints for large areas or steep slopes, and larger ponds may require a professional installation.

Pond Liner Calculations

Measure the length, width and depth of the place you intend to put your pond to determine the liner size you need.

  • If you have an irregular shaped pond, include the widest part of the shape as the width and the longest length.
  • Add your measurements to the following formulas to determine the liner size.
  • Allow an extra 6 inches to go under and behind the edging stones.

Water Garden Calculations

Liner length

Maximum pond length + 2 x pond depth + 6 inches

Liner width

Maximum pond width + 2 x pond depth + 6 inches

Pond capacity

Length x width x depth x 7.50 = gallons (in. ft.)