It’s rare that the urban wasteland behind King’s Cross is credited with encouraging us to embrace nature. But the recent opening of the country’s biggest open-air swimming pond there – a 40-metre long chemical-free pool surrounded by wild flowers and grasses – is driving a surge in demand for similarly bucolic pools in our back gardens.  Forget swimming among the murky depths of Hampstead ponds, where you never know what slippery creatures might be sharing your dip. Swimming ponds have crystal clear water and the bathing area is separate from the beasties.  “When you’re planning to build a swimming pond, you need to decide how big an area you want to swim in, then double it to account for the surrounding planting,” says Paul Mercer, director of The Swimming Pond Company, who is currently working on a natural swimming pool in Suffolk whose water laps up to the edge of the new-build eco house.  “You open the fully-glazed walls of the master bedroom and walk straight onto the stepping stones,” says Mercer. This particular pool is costing £180,000 to build, but Mercer reckons to budget from £50,000 for an 80m2 swimming pond. You can enjoy the natural experience in small, urban spaces too. Clear Water Revival – who have seen demand for natural pools rise by 80 per cent in the past year – say a 15m2 natural plunge pool would cost from £15,000.  Existing ponds or conventional pools can be converted into swimming ponds – or you can build from scratch – and there are great benefits. Swimming ponds – where plants keep the water clean by removing its nutrients – don’t need covering over when summer’s over and you can’t heat them so they’re cheap to maintain. “The biggest job of the year is cutting back the plants in November,” says Mercer.  Natural pools – where the water is cleaned by a biological filter – can be heated and covered, “just like a chlorinated pool. You can still include plants in your pool design but cleverly separate them from the swimming area,” says Kate Hawkins from Clear Water Revival.  Unlike traditional swimming pools, which spell endless maintenance to many prospective buyers, natural pools are more likely to recoup their cost and potentially add to the property’s overall value and desirability.  “They are still uncommon, which makes it difficult to determine their value, and their worth is definitely in the eye of the beholder. But for someone who really wants a swimming pool, it could add significant value. There’s something rather romantic about swimming in a natural environment,” comments Lindsay Cuthill, head of Savills Country Department, who is marketing Glen House near Tonbridge in Kent for £4.5m, a Grade II-listed Arts and Crafts house with 10.5 acres of land that include a natural swimming pool.  “Once you’ve had a swimming pond, you can’t live without one,” says Paul Mercer, who swims in his every day. “I’m looking at it now – there are dragonflies and swallows hovering over the water and butterflies in the border beyond. It’s full of life all the time and even in the middle of winter, a swimming pond can look quite magical.”  The Austrians and Germans would agree – they love their natural swimming ponds – but elsewhere in the world, the super-rich have a different view on what makes for a magical swim.  Often that means as much high-tech gadgetery and architectural pizzazzery as possible and one house that delivers both is Villa Escarpa on the Algarve. On sale for €3.7m (fineandcountry.com), its living space floats on an eight-metre wide overhang and the pool cuts through the centre of the u-shaped building and hangs above the valley beyond.  Never a place to stint on bling, Sardinia’s Costa Smeralda is home to a pool that inspired a Bond baddie’s shark pit. Villa Amoras - on sale for €15m (beauchamp.co.uk) – was the prototype of the villain’s house in The Spy Who Loved Me. And the swimming pool – which, in the film, was full of sharks – runs outside and in, beneath the glass floor of the living room. While your partner is relaxing on the sofa, you can demonstrate your backstroke beneath their feet.  In Cannes, a pool is simply about showing off. Inspired by Palladio, there’s a Venetian-style "palais" on sale for €95m (john-taylor.com) that appears to float on water, the columned mansion framed by a 25m swimming pool and private lake. And why bother with the Croisette when you can recline on your lilo and watch movies in the swimming pool of The One, a newly-built four-bed villa with a cinema screen at one end of the long infinity pool. That pleasure will cost you €8.45m (home-hunts.com).  “On the French Riviera, pools are also often designed as an extension of the property’s architecture and décor with opulent mirrored infinity pools and Jacuzzis bedecked in marble and onyx,” comments Julien Mendjisky from John Taylor France. “There’s also a trend here for the swimming corridor, where you exercise by swimming against a current,” Mendjisky adds.  Some private villas also have the kind of huge freeform pool you associate with a large luxury resort. In the Maldives, Villa 11 – on sale for $15 million (akinternationalestates.com) – has the biggest freeform pool in the Indian Ocean, all 6,500 sq ft of it with a sunken lounge area and over-water trampoline accessed by a bridge and waterslide.  And in New Jersey, the owners of one modern mansion – yours for $4.199m (dianeturton.com) – commissioned the pool design team from Orlando’s Disney Resort to design their Olympic-sized, freeform novelty with a beach-style entry, grotto, water slides and a water park-style "lazy river" attraction.  Some pools come with architectural cachet such as the one at John Lautner’s Stevens’ House, built in 1968, in Malibu. The beachfront wood and concrete house, priced at $19.75m (knightfrank.com), was designed to resemble waves and includes a pool in a hull-shaped room with uninterrupted ocean views.  In La Jolla, San Diego, architect Wallace Cunningham was inspired by Japanese landscapes when he designed Brushstroke – priced at $12.7m (christiesrealestate.com) - with a black, rimless pool shaped like a cat’s eye, whose water cascades 14 feet down into the surrounding gardens.  They’re gorgeous and glitzy, but it could be a while before the billionaires of Cannes or California embrace natural swimming. Then again, they’ve done it in King’s Cross…
Should you opt for an opulent mirrored infinity pool, swimming corridor or natural pond? Zoe Dare Hall dives into the diverse world of luxury swimming pools