How to Apply Mortar Over a Pond Liner

Written by brenda priddy
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How to Apply Mortar Over a Pond Liner
Adding mortar to a pond is useful for many reasons. (by the pond image by Quennie Chua from

A pond liner is a flexible plastic liner laid over the interior of a pond to prevent the water from leaking into the ground, and to prevent the pond from becoming muddy. You can install mortar over a pond liner to add strength, then you can add rocks and decorative elements. Adding the mortar is a simple process, but it's important to keep the mortar wet during the curing process to prevent cracking. Always wear a dust mask, eye protection and work gloves when working with mortar.

Skill level:

Things you need

  • Dust mask
  • Eye protection
  • Work gloves
  • Large container
  • Mixing trowel
  • Plastic cement
  • Sand
  • Concrete reinforcement
  • Flat trowel
  • Large rocks
  • Cement sealer
  • Paintbrush

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  1. 1

    Mix the mortar using three parts sand to one part plastic cement. Add 1½ parts of concrete reinforcement for stability. Mix the ingredients in a large container. Add enough water to create a mud-like paste.

  2. 2

    Spread the mortar over the liner with a flat trowel. Spread the cement to a thickness of about 1 inch.

  3. 3

    Press large rocks into the mortar to create borders and shelves for plants or fish. Press the rocks around the edges of the mortar to hold them in place. Spread a thin layer of mortar between the rocks for additional bonding and to create a watertight seal between the rocks.

  4. 4

    Water the surface of the mortar every hour. The cement must remain damp throughout the entire curing process or it will crack.

  5. 5

    Seal the mortar with a cement sealer. Apply the sealer with a paintbrush. Allow the sealer to dry for 24 hours.

  6. 6

    Fill the pond with water as soon as the concrete sealer dries. This is the best way to maintain the strength of the cement inside the pond.

Tips and warnings

  • If desired, you can increase the thickness of the mortar up to 3 or 4 inches thick.

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