How to design a natural swimming pool - Grand Designs Magazine
Grand Designs' Nina and Dan's spectacular home with its natural pool

How to design a natural swimming pool

Building a low-nutrient natural swimming pool will provide the perfect space to swim and relax and create a natural habitat for wildlife and flora in your garden

By Sara D'Souza |

Wild swimming – be it rivers, tarns, lakes, ponds or oceans, has a myriad of physical and mental health benefits, and there’s been a recent uptick in bringing those benefits to your own home by installing a natural swimming pool. Natural pools also provide a habitat for a wide range of wildlife and will introduce biodiversity to your garden – especially important as our need to zone our gardens and re-connect with nature. The term natural swimming pool or swimming pond can be used interchangeably, as they both function in the same way.

And, how can anyone forget Grand Designs’ Nina and Dan Simon’s spectacular biodiverse waterside home in Chichester (season 22, episode 5), where they created a pool (main image) that they can dive off the deck outside their kitchen right into. It was a pool that sparked inspiration, when people realised the vast possibilities available to them with natural swimming pools in residential gardens.

Tim Evans from the fantastic Gartenart, the UK’s leading swimming ponds and natural swimming pools provider, talks Grand Designs’ through everything from how they work, to how to maintain them. Here’s how to take the plunge.

How do natural swimming pools work?

Tim explains that “a swimming pond or natural swimming pool is essentially a low-nutrient wildlife pond. It is similar biologically to a mountain lake, for example, where there is naturally very little nutrient input from the surroundings. In a garden setting we need to both a) minimise nutrients coming in from outside the system, and b) circulate the water through filter material to reduce the nutrient level as much as possible. In these low nutrient conditions the water is completely clear and there is very little algae growth.”

“Most swimming ponds have a regeneration zone as part of the planting zone, either surrounding or to one side of the swimming area. Usually the regeneration zone will be a deeper aggregate bed, with a specific material to reduce nutrient levels, through which the water circulates to keep the nutrient level low.”

Create a secret hideaway in the garden with a natural swimming pond

Image credit: Gartenart

What’s the best positioning for your pool?

When it comes to positioning, Tim says it’s “best to have a reasonably open location, and particularly not directly under tree branches. The ground should also be reasonably flat – it can slope to some degree, but obviously the more it slopes the more any banks or retaining structures will have a visual impact.”

He adds that “it is up to you whether you site it close to the house or further away – it depends how you are thinking of using it, and on other site factors”.

Think about shape you want too, dependent on your landscape and preference, there’s no rules with it. An irregular shape can be more in keeping with a wild pond and blend more naturally into its surroundings and is more frequently called a natural swimming pond, while a more traditionally shaped rectangular pool is often called a natural swimming pool. Gartenart’s incredible portfolio showcases everything from natural pond designs to formal pool designs to pond and lake conversions.

Unlike regular swimming pools, natural swimming pools don't use any chemicals

Image credit: Gartenart

What are their benefits?

Tim explains, how “a swimming pond is part of your garden – because it is alive it is constantly changing throughout the seasons and from year to year. We do not add anything which harms living organisms – our principle, as described above, is always to keep the nutrient level low. Because it is alive, but also healthy, the water has a presence to it which is very unlike conventional pool water or even sea water.”

“It has a quality which is almost meditative… you can appreciate this by being next to the pond, and particularly by getting in the water.  People use different words to describe it – people commonly call the water ‘silky’. Gartenart has open days where you can test this out for yourself.”

“Another benefit has become more apparent in recent years with the increased interest in cold water immersion. In the summer a swimming pond is a swimming facility and social hub, and it looks beautiful. However in the winter it is a cold dipping pool, and more and more we find that clients are getting in all year round.”

A natural swimming pond featuring crystal-clear waters

Image credit: Gartenart

Do you need to get planning permission?

Planning permission is not usually needed to create a natural swimming pool in your garden. Two of the main criteria to look out for that could require planning permission are if you live in a listed building or if your property is within an Area of Outstanding Natural Beauty (AONB). If you do require it, Gartenart is experienced in getting planning permission and can help advise with specific situations.

A huge benefit of Natural Swimming Pools is how clear the water is

Image credit: Natural Swimming Pools

What should you plant in and around them?

When it comes to planting, Tim explains that “in the water you should plant water plants which do well in low-nutrient conditions. For example we use Iris pseudacorus, Typha gracilis, Carex acuta, Lythrum salicaria, Caltha palustris, and many others.”

“Outside the water and around the pond you can plant grasses or other land plants if you want to create a fuller look. However after a few years the swimming pond plant growth will be quite thick so you wouldn’t need the plants around the outside”.

David Pagan Butler from Organic Pools adds that “plants are an obvious ally in maintaining water quality in a natural pool, but the importance of the small creatures and microorganisms should not be overlooked, as they are crucial to maintaining clean water.”

“I visualise that my pool is filled with the freshwater equivalent of bio yoghurt. Every niche is filled with beneficial microorganisms keeping the water healthy and fresh. It is important that the circulation system doesn’t impair the effectiveness of these microflora and fauna. That’s one of the reasons why my pools use bubbles to gently move the water.”

Swim amongst lily pads and rushes in your own garden

Image credit: David Pagan Butler

How to maintain your natural swimming pool

Tim talks us through pool maintenance: “We always say a swimming pond needs half a day of maintenance per month. Less for smaller ponds, two – three hours per month and more for larger ponds, around four to five hours per month.”

“GartenArt has a team which can do this, or you or your gardener can do it. Maintenance mainly consists of brushing the surfaces and vacuuming out any debris which has accumulated at the bottom.”

It's fairly easy to maintain your natural swimming pool

Image credit: Gartenart

How did Grand Designs’ Nina and Dan create their natural pool?

“The couple wanted their Grand Designs Chichester pond house to promote wellness and relaxation, partly inspired by a forest spa they had visited in Thailand, where walkways weave around boulders, with pools of water have a calming effect.”

“To create their own watery paradise (Dan and Nina worked with the team at Natural Swimming Pools), they reconfigured the stagnant pond that had been dug more than a century ago to drain the surrounding land. First, 1.5m of sludge was removed from the bottom, which amounted to around 500 tonnes, and allowed to dry so it could be used to landscape the garden. Further excavation created the swimming pond, while a shallower pond, separate from the main body of water, continues to act as a natural drain.”

“The swimming pond has two parts separated by an underwater wall – a swimming zone and a regeneration zone with areas of gravel and clay,” explains Dan. “Water filters through the gravel and is pumped through a network of pipes to prevent stagnation. Plants growing in the clay feed off nutrients in the water, preventing algal bloom and keeping the water crystal clear.”

Grand Designs' Nina and Dan's spectacular home with its natural pool

Image credit: Natural Swimming Pools