Swim spas: a pool that fits a terrace

Yes, against an adjustable current, which is more like swimming on a treadmill than swimming lengths. The Nedar 4.3 at 430 cm suits steady front crawl and aqua exercise; the 5.2 and 5.9 give a taller or stronger swimmer more room ahead of the jets. Come and try one before you decide, because stroke and preference matter more than the spec sheet.

A Nedar weighs 1,500 to 2,100 kg empty and up to 12 tonnes full of water and people, so it cannot sit on tiles over sand or on an ordinary terrace. It needs a reinforced concrete slab, which we pour at 85 to 110 euros per square metre a week before delivery, or a structural check if an existing slab is proposed. Roof terraces are out unless an engineer says otherwise.

A swim spa standing on a slab in your garden is normally an appliance, not a construction, and needs no licence. If it is excavated and set into the ground, some councils treat it like a pool and ask for a comunicación previa or a licence, and urbanisation statutes may have their own say. We cannot give legal guarantees, so check with your council and community before choosing a sunken installation.

The 5.9 Dual has two separate bodies of water with their own pumps and heaters: a swim zone you can keep at 28 °C for exercise and a spa zone at 38 °C for afterwards. The single-zone 4.3 and 5.2 are one temperature for everything, which is cheaper to buy and run but means choosing between a cool swim and a hot soak. Families who want both on the same evening go for the Dual.

More than a hot tub because there is seven to ten times the water. In Mallorca at around 0.22 euros per kWh, expect 90 to 130 euros a month in summer and 180 to 260 in winter, depending on the model, the temperature you hold and how often you swim. A good cover kept closed and a swim temperature of 28 rather than 32 °C make the biggest difference.