Top Tips For Designing A Wild Swimming Garden Pond

A traditional outdoor swimming pool rarely does much for the aesthetics of your garden, besides needing a lot of chemicals and equipment to keep them in good condition. A practical solution that is becoming more popular here in the UK is the natural swimming pond. Here’s a look at how to plan one for your garden.

What are the benefits of outdoor swimming?

Swimming outdoors in unheated water helps many people manage both their physical and mental health. All exercise does us good, but swimming is particularly effective because it works out the whole body, and gets the heart pumping while putting less stress on the joints than other strenuous exercises such as running. 

There are also proven benefits to outdoor swimming in water colder than we are accustomed to. This is because the shock of the cold causes the adrenaline levels to surge, and the stress hormone cortisol is released. At the same time, a rush of beta endorphins flood the body to help counteract the shock, as this article in Science Focus explains. 

Endorphins can induce a sense of euphoria, which is why so many people find that wild swimming helps them manage their stress and other mental health issues such as depression. Scientists have found that repeated exposure to cold water can even lower inflation inflammation and help the body cope better with other stressful situations. 

The celebrity chef Hugh Fearnley Whittingstall is a committed open water swimmer, and he explained in a recent BBC interview that it helps him to manage his stress levels. He has a natural swimming pool in the garden of his cottage in Devon, where he even breaks the ice to swim in the depths of winter!

He describes the benefits of the exercise, and he also enjoys the wildlife that the pool attracts to the garden, such as kingfishers, grass snakes, and water rats.

How do natural swimming pools work?

A natural pool can either be based on an existing pool or dug out with an excavator.  There are a number of different systems or models for swimming ponds, but the simplest just use plants in a regeneration area, which act as natural water purifiers, surrounding the swimming area.  This is known as a Hydrobotanical System. The addition of pumps to gently recirculate the water can improve their effectiveness.   

The minimum recommended size for a family of 3-4 is about 1005m2 to get the most benefit from the pool, which should have a depth of 2m -2.5m in the deepest part to prevent sediment being stirred up by swimmers.   The regeneration area should take up at least 50% or more of this. The swimming area is surrounded by a tier of marginal pond plants, which act as natural water purifiers. 

The plants are bedded in gravel or other filtration materials rather than soil so that they extract nutrients from the water rather than from the soil. This helps to keep the water clean and clear. The water is circulated through this organic filtration zone via hidden pumps on a continual basis.

The key to maintaining a healthy pool is to keep the level of nutrients well balanced so that the aquatic plants can thrive, but nuisance algae and blanket weed is kept at bay. 

The pool is lined with durable waterproof material, usually in a dark green colour to maintain the natural appearance and to help with heat retention.

Where is the best place to site a natural swimming pool?

The pool will obviously take up quite a lot of space, so you need to have a reasonably large garden to avoid overwhelming the natural proportions of your outside space in comparison to the house. It’s best to construct it in a level well drained site away from mature trees, to avoid excess leaf drop that could pollute the water.

If you have a large garden consider siting the pool closer to the house, so that you get to enjoy the beauty of it as a water feature from your window. The pool will also attract wildlife, such as birds, bees, and butterflies, so you will be able to observe them going about their lives as well.

What plants are best for natural swimming pools?

Plants that will thrive on the margins of a pool include Marsh marigold, Purple loosestrife, water mint, hop sedgeCyperus sedge, Sweet galingale, True bulrush, Typha,  flag iris, and water lilies. It’s best to choose species that are native to the UK wherever possible because these will help to provide food for wildlife and boost the natural biodiversity of the area.

Note that whilst the holy grail for swimming ponds is to minimise the level of nutrients in the water to eliminate the growth of algae and blanket weed, too few nutrients can be counterproductive and limit the growth of plants which are then unable to properly purify the water.  So in some instances therefore additional fertilisation may be needed.

How much maintenance do natural swimming pools need?

The natural swimming pool is low maintenance, unlike a traditional outdoor pool. No chemicals are needed to add to the water, and there is no need to drain the pool to clean it.  The plants will do the job of keeping the water clean, and they will just need some seasonal pruning to keep them in good condition. 

Do you need planning permission to build a natural swimming pool?

In most cases you will not need planning permission, but it is always best to check with your local authority first. If you live within a conservation area or an Area of Outstanding Natural Beauty (AONB) then you will need to apply for planning permission. However, it is unlikely that permission will be refused, given the environmental benefits of a natural pool.

Are there any other points to consider?

You should think about how the garden can be accessed if you need an excavator to dig out the pool. Before work begins, decide what size, shape, and depth the pool will be, and how you will access it, such as via steps or a ladder. The pool should be deep enough to avoid excessive water evaporation, and allow you to dive in safely, should you wish to do so.

The pool will need plenty of space around the margins for the planting and filtration material, so bear this in mind when calculating how much swimming area you require. You will also need to install a terrace or an area of decking to provide access to the pool.

The cost of having a natural pool installed depends on the size, and how difficult the area is to access. It will probably be a significant cost if you want to hire a specialist natural swimming pool company. The cheapest option would be to hire the equipment and build it yourself, but consider if you have the necessary skills to do this.