Installing preformed garden ponds

Tools and Equipment

To install preformed garden ponds, you will need:-

  • Builders sand
  • Sifted soil
  • Wooden stakes
  • Tape measure
  • Straight edge
  • Spirit level
  • Pole for tamping down the soil around pond edge
  • Tools for digging and a rake

Marking out

For a preformed liner that is symmetrical in shape. Turn the liner upside down and mark the shape on the site.

For an irregular shaped preformed liner. Place the liner the right way up on the site and ensure it is level. Using a level and a straight edge, mark the shape on the site with wooden stakes. Remove the liner and lay a hose pipe around the stakes to show the shape of the pond.


Around the the marked shape of the pond, and allowing for the excavation to be 4” (10cm) longer and wider than marked. Knock in a regular series of wooden pegs and level the tops of the pegs using a straight edge and spirit level. These will be used during the excavation to check that the shelves and base of the pond are level. Placing the straight edge across any two pegs will give you a level point to check by measurement, the level and depth of the excavation.


Measure the depth of the shelves and excavate the whole pond, plus 4” (10cm) in length and width, to the shelf depth plus 2” (5cm).

Loosen the soil in the base of the excavation using a rake and remove any stones. Place the preformed garden pond liner in position within the excavation and press down firmly. This will will mark the base of the pond.

Remove the liner from the excavation. Measure the width of the shelves and mark their positions. Excavate the final section of the pond using the base and shelf markings as a guide to the total depth of the pond plus 3” (7.5cm). Ensure the bottom of the excavation is level.


Carefully check the excavation and remove all stones and sharp objects. Lay 2” (5cm) of builders sand in the base of the excavation. Don’t sand the shelves.

Place the preformed garden pond liner into position. The lip of the liner should be slightly below the ground level and be level across its length and width. If it’s not, then remove and adjust the excavation.

When you are satisfied with the position of the liner, fill with water to a depth of about 6” (15cm). Back fill around the liner using sieved soil and tamping down carefully, taking care not to damage the liner. When the back fill reaches the level of the water check the liner is still level and adjust if necessary. Repeat this process until the back fill is 2” (5cm) or 3” (7.5cm) below the lip of the liner.

Finish by edging the preformed garden pond with the material of your choice. If paving is to be used, excavate the width of the slabs to a depth of 4” (10cm), and lay a concrete base. Fill the lip of the pond by packing it with sand. The slabs can then overhang the pond to conceal the lip. Lay the paving slabs using sand and cement.

Take care not to drop cement into the pond. It is toxic to pond life and will have to be cleaned out and the pond water changed.

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