Introduction

Ponds don't have to be dug in the ground. A formal pond with a raised edge using bricks or concrete facing blocks makes wonderful waterside seating. Raised ponds are also much safer if there are small children around, especially if you construct the edging about 450-500mm (1ft 6in-2ft) high.

The water must also be clear and to achieve this you will need to install a pump to recycle the water, or establish a careful balance of pond life, which includes oxygenating plants (at least 10 per square meter of water surface), snails and fish. A successful balance creates a food chain, which excludes the green algae that stains surfaces, clouds the water and kills pond life.

The best way to construct a raised pond is to use a low, double-skin construction for strength and to make sure it is watertight in case of leaks in the liner. The inner skin can be constructed of plain concrete blocks (decorative bricks or blocks can be saved for the exterior walls). Build the walls with a space between that matches the width of the coping stones used to finish the top of the walls. You will need to lay good solid foundations to support the walls, so lay footings of 100-150mm (4-6in). Raised ponds can be lined using a made-to-measure prefabricated rigid liner, which reduces the number of creases at the corners that you will have if you opt for a flexible plastic liner, but these often don't have overflow or outlet facilities. The top edge of the liner is trapped under coping stones making it invisible.

Step by Step Instructions

1 Constructing the pond

The essential feature of a wall is that there is a firm, level, foundation along its entire length consisting of a concrete base, called the footing. Pour concrete into a prepared trench dug to expose firm and stable ground. Use plain concrete blocks inside the pond for the double skin.

2 Adding the liner

You will need a liner large enough to cover the sides and bottom - add a layer of damp, smooth sand at the bottom of the pond to stop the liner from being punctured by stones when the water is added. Let the liner sag into the pond and arrange it so it lies over the edges. Pleat the edges to neaten the corners.

3 Add water

The liner should overhang the edges sufficiently so that when the water is slowly added, its weight pulls the liner gently down and against the sides. Help the liner in - you want it to lie flush against the bottom and sides.

4 Adding the coping

The overlapping edges of liner can be trimmed off leaving a wide overlap. This will be covered and hidden from view by a row of coping stones. Bed the coping onto the wall with mortar, checking constantly that it is level.