Garden Water Features Q and A

I plan to install a pool in my garden. Are there any general rules about siting?

Pools should be sited in an open, sunny position where plants and fish can flourish. Shady areas are not suitable and leaves and other vegetation blown into the water may produce gasses that can kill many of the fish.

What constructional materials are available?

Concrete involves a lot of work and for DIY purposes has been largely superseded by plastic of various types. Glass-fibre pools are fairly small and quite expensive, but being pre-formed are simple to instal. Vacuum-formed pools look rather like glass-fibre but are cheaper; they are somewhat fragile and can have a short life. Flexible liners are now by far the most popular constructional material; they are available in polythene, which is the cheapest and least durable; laminated PVC, which is far stronger and ideal for most domestic pools; and butyl rubber, the toughest and most expensive, which is especially suitable for large projects such as lakes.

I want to make a liner pool, but how do I calculate the size of sheet needed?

The size is calculated by taking the greatest length and greatest width and adding twice the maximum depth to both these figures. This gives the total liner area.

Should a pool be all of one depth? And how deep should it be?

In any pool you need to create a balanced environment of plants and fish. To achieve this both shallow- and deep-water plants should be grown. These are placed in baskets either on a ‘marginal’ shelf around the edge of the pool or on the bottom. The shelf should be 225 mm (9 in) below water level and as much wide. Contrary to popular belief a garden pool no deeper than 600 mm (2 ft) is quite sufficient to grow a wide selection of lilies and other deep-water plants.

How can I construct a pool using a liner in the central part of my lawn?

After calculating the size of the liner, mark out the shape of the pool and surrounding coping. If curves are involved these can be set out by swinging a line from a stick acting as a radius point. Lift the turf and stack it for use elsewhere in the garden. Dig out the entire area within the marked shape to a depth of 225 mm (9 in) sloping the sides slightly. Next mark out the marginal shelves and dig the remaining area out to a depth of 600 mm (2 ft), again sloping the sides; you can make a simple template to check the angle, which should be approximately 20° from the vertical.

Remove any sharp stones from the bottom and sides and cover all the inside surfaces with a 13 mm (½ in) layer of damp, soft sand. The liner can now be gently positioned and the edges weighted down with bricks, water being run into the pool to mould it to shape. When the pool is full, slit any wrinkled edges of the liner to lay it flat and trim it to size so that a 225 mm (9 in) border is left all round the edge of the pool. Coping should be finally laid on a bed of 3:1 mortar.

I have a small sunny corner in the garden, about 3 x 3 m (10 x 10 ft). Is this big enough for a pool?

In general terms the bigger the pool the better, as a large volume of water supports a balanced environment more easily than a small one. A pool of 9 m2 surface area is quite adequate, but remember that you will need some form of coping around the edge, which will reduce the overall size. As a rule a pool 2 m (6 ½ ft) square is a practical minimum to support plants and fish.

With young children in the family, I am concerned about having a pool at ground level. Are raised pools practical, and how should they be built?

A raised pool is inherently safer than one at ground level and can be constructed in a similar fashion to a raised bed. In order to avoid rendering the inside, which can often lead to leaks, fit a plastic water tank so that the top is 50 mm (2 in) below the level of the coping. Fill the space between the tank and the sides with soil: this can later be planted up to provide a softening influence. A submersible pump can be fitted to feed a small bubble fountain, the cable being hidden by surrounding foliage and taken through a hole in the surrounding walls.

I have seen an attractive millstone fountain in a local garden which was most attractive. Can I make one?

Millstones, boulders, and large thick pieces of slate, marble, or granite can all be used to make most attractive water features.

They should be drilled to accept a 13 mm (½ in) diameter copper pipe. A sump forms the basis of the composition and this can be made from a plastic or galvanised water tank. Excavate a hole to accept the latter so that the top is flush with the ground surface, removing sharp stones or other projections from the bottom. Make sure the tank is level. Now build two brick piers off the tank bottom. These are finished just below the top of the tank so that the millstone, when it is positioned on them, projects above ground level. A submersible pump is placed between the piers at the bottom of the tank and is connected to a pipe that passes through the stone and is cut off flush with the top. A circular water tank can usually be obtained to fit the diameter of a millstone, but if there is a gap this can be bridged by large loose cobbles or bold foliage, the latter making an attractive contrast to the hard stone. Finally, fill the tank and switch on the pump.

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