How to construct a formal pond

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Build a formal garden pond

Creating a formal shaped pond is possible from bricks or blocks as:

  •  A raised pond - wholly or partially above ground. Suitable as focal points with pond plants or fish ponds. They are not easy for amphibians to climb in and out of so only suitable for airborne wildlife.
  • A below ground but formally shaped pond. Suitable as planted ponds, fish ponds or wildlife ponds if the edging is made wildlife friendly

To construct a formal pond

Dig out the pond profile - work from the outside edge of the pond and dig the shelf areas and the deeper water areas

  • Koi ponds have special requirements - more depth and specialist filters
  • Other formal ponds for goldfish and plants can be made to a total depth of 60 - 75cm(2ft - 2ft 6")
  • Create shelf areas at depths of 15cm and 30cm (6"and 12") below finished water height for plants either in the corners or between 3 of the edges.
  • Make the shelves cover one quarter of the surface area as formal ponds tend to have more waterlilies and less marginal plants.
  • To safely add plants to a koi pond - add a wide shelf area with a barrier of brickwork on the deep water edge of the shelf that allows small fish and water to flow through but keeps the larger fish away from the aquatic water plants.

Work on the blockwork construction

  • Dig a shelf to sink foundations and the first block below the garden level of soil.
  • It is important to ensure this foundation shelf is level or any further building above it will not be level
  • Build upwards in grey blockwork.
  • Build face brick to match the garden around the skin of blockwork.
  • The face bricks should extend one brick higher than the grey blockwork

Lining the blockwork shape with flexible liner

  • The rough blockwork should be covered by a geotextile membrane. Fold it into corners and removing excess in the corner folds
  • Measure and choose your liner requirement. See Lining the pond hole for a wildlife pond
  • Lay the flexible liner over the underlining making sure it lays on the base of the pond and reaches all the corners
  • Start to add water to weigh down the liner.
  • Stop water filling and adjust the liner before too much weight is on it. Pull out the creases and try to put the folds in the corners
  • Continue adding water and check creases and folds
  • Be very careful with the corner folds checking that all edges of liner are higher than the top of the outer face bricks.
  • Stop adding water before you reach the last block


  • Put in place any pipework for filters or pumps making sure the pipe is as high as possible to the top of the face bricks.
  • You want the top of any pipe to be to the top of the face brick so water can fill well up the face of that outside brick.
  • Take the geotextile and the liner smoothly over the top of the lower inside block and finish by folding it over the higher outer brick wall.
  • The inside blockwork wall can then be made up to the same height as the outside face brick wall. Mortar an outside decorative brick onto the liner in line with the hidden blockwork. When you look across the formal pond you see matching brick to the outside brickwork.
  • The liner is now laying up between the 2 lines of brickwork at the top
  • Complete the build with a coping stone or slab mortared across the 2 lines of brick trapping the liner in place laying above the outer brickwork.
  • When all mortar is dry trim back the surplus liner by cutting away from under the coping stone.
  • The facing brick and mortar line will be under the water level and will need sealing with a waterproof sealant to prevent alkaline leaching
  • Raise the water level to its full height - half way up the inside facing brick