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How to Apply Mortar Over a Pond Liner

By Brenda Priddy ; Updated September 21, 2017
Adding mortar to a pond is useful for many reasons.
by the pond image by Quennie Chua from Fotolia.com

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 add mortar over a pond liner to add strength and you can add rocks and decorative elements to it. Adding the mortar is a simple process, but it is 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.

Mix the mortar in a ration of three parts sand and one part plastic cement. Add in 1 ½ parts of concrete reinforcement to add stability to the mix. Mix the ingredients in a large container. Add in enough water to create a mud-like paste.

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

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 water-tight seal between the rocks.

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

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

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.


Things You Will Need

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


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

About the Author


Brenda Priddy has more than 10 years of crafting and design experience, as well as more than six years of professional writing experience. Her work appears in online publications such as Donna Rae at Home, Five Minutes for Going Green and Daily Mayo. Priddy also writes for Archstone Business Solutions and holds an Associate of Arts in English from McLennan Community College.