THEY’RE NOT CHILLY, BUT DON’T LET THE DUCKS IN ...

How do you clean it?

IT involves splitting the pond into two, a deeper swimming area (2m plus) and a shallower ‘regeneration zone’ (1.5m), with natural filters, such as gravel and shingle. Also vital are wetland plants, such as aquatic irises and lilies to help discourage phytoplankton (microscopic algae that can turn water green) and other bacteria.

Once cleansed, water flows back into the swimming zone thanks to an electric pump or an artificial waterfall.

Can you heat it?

YES, but heating can promote blanket weed. Most owners just swim in summer. Temperatures can range from 16c to 22c. The shallow gravel area helps the water warm naturally, says Paul Mercer, of the Swimming Pond Company.

Animal life?

DON’T buy a pond if you are not happy swimming with frogs or newts. It rapidly attracts all manner of pond life, including birds. Discourage fish and ducks. Ducks produce faeces and eat filtration plants, while fish eat the insects that help to minimise harmful bacteria.

What’s the cost?

ABOUT £50,000 to £65,000 for a basic pool (10m by 5m) — similar to a conventional outdoor pool, up to £200,000 if you have all the trimmings, lighting, decking jetty and summer house But it will cost less to maintain, as the water never needs to be changed.

How long will it last?

A MEDIUM-SIZED pond can take eight weeks — digging out, lining and edging and fitting the filtration system before decking and other features are installed. Then it can be filled.

It should last a lifetime. One pond maker, Gartenart, guarantees its liner for 50 years.

Health benefits?

COLD-WATER swimming is said to boost circulation and the immune system, and may even make you look younger, say devotees. It has an anti-inflammatory effect, promotes a sense of well-being and stimulates brown fat — pockets of high calorie-burning fat distributed throughout the body — to work even harder.