Build Your Own Organic Swimming Pond


Conventional swimming pools are pointless here in Ireland, as we can only use them for around three months a year. But a natural swimming pond can be a haven for wildlife when you aren’t using it for luxurious swims. The idea of wild swimming at home is a movement gaining momentum as people realise how inexpensive it is to build a natural swimming pond. David Pagan Butler of Organic Pools tells us how we too could have a little piece of paradise in our garden.

swimming pond1

This is a natural swimming pool. The swimming area is in the middle, and the outside area is for plants and animals that keep the pool conditioned. The water is gently circulated by a system of bubble-powered pumps.

A natural swimming pool is simple to construct and works perfectly. Indeed there are many people who would have you believe this is too complicated for the nonprofessional. That is nonsense. It is hard work but deeply rewarding and completely achievable.

Why do we smile, or for some of us, struggle to contain our gushing beams of joy, the first time we see a natural swimming pool? Is it because inside we know this is so right, giving something back to nature by the creation of a small wilderness? Perhaps we have always secretly wanted to jump into deep luscious pools of freshwater but have been frightened off by decades of myths listing battalions of hazards awaiting any adventurous swimmer.

Today, flourishing on a tide of awareness, we see living freshwater with fresh vision. Thankfully now, we can jump in as happily as an otter. A natural swimming pool, or the name I prefer – organic pool, has been the most magical addition to our home. It is a beautiful place to observe nature throughout the seasons, bringing us closer to wildlife. The multitudes of species that now live in the pond are an endless fascination to my children, who spend hours observing them from the small jetty which traverses the shallows, dangling down their nets to catch water boatmen or dragonfly larvae for a close up look at these incredible creatures.

Then come the birds, visiting the pond in the morning and evening. The grey wagtails, skylarks, dunnocks, gold finches and the formations of swallows circling and skimming the surface to drink or bouncing with delicious splashes to bathe. Dragonflies patrol, snapping up crane flies and cabbage white butterflies and buzzing into skirmishes with intruders. House martins peck at the water’s edge collecting mud for nests. Bats flit in and out of their invisibility cloaks in the evening glow reflected on the pond. And sometimes, in the skidding sunbeams of the morning, I may catch the iridescence of a kingfisher feeding on water beetles.

Plunge pool

Haven’t got a lot of space? Then perhaps you’d prefer a beautiful plunge pool.


This pond has become another stepping stone for wilderness. Local native flora and fauna has found its way in and flourished, increasing local biodiversity. If we create more ponds we will contribute to re-establishing our countryside’s diminishing freshwater network. And of course there is the swimming. Our children are learning to swim in a healthy environment free from the unpleasant effects of disinfectants found in most pools. I imagine, one day we will look back and wonder how we ever thought it was reasonable to let our children swim in anything other than natural water. Until now only people with a fair amount of cash, typically from around €70,000, have been able to consider having one of these pools built for them. But there is a different way.

I built my organic pool, an 180m2 pool, for roughly €8,000. And knowing what I know now, I could do it for considerably less. It takes a lot of work but, after all you’ll be saving tens of thousands of euro by building it yourself, and I can’t think of any work more rewarding than creating a pool.

sandy beach

You can even make a sandy beach for your natural pool.

Once you see how easy it is to construct one of these pools, the process will be demystified and you’ll think it’s a project you could happily be immersed in. Organic pools work with nature to provide clean healthy water for swimming. Plants and animals in the pond condition the water without the use of chlorine or other disinfectants. So the water doesn’t sting your eyes, bleach your skin, corrode your teeth or make your swimming trunks fall apart. Instead, the water holds a vibrant and diverse ecosystem, teeming with micro-organisms that constantly filter and devour any human pathogen that has the misfortune to plop in.

The key to promoting a diverse eco-system is to prevent one species from dominating the pond. In a poorly created pond the usual dominating big baddy is blanket-weed. Blanket-weed (Cladophora superphylum) is the most common filamentous alga forming dense swathes over ponds in bright warm weather where phosphate and nitrate levels are high. The key to control the growth of algae is to restrict the nutrients entering the pool. If the nutrient level is low enough, plants successfully compete with algae. As the plants grow they accumulate the nutrients in their structure and further deprive the algae from flourishing.

As well as plants there are other vital allies – the myriad of micro-organisms that make up the zooplankton living in every cubic millimetre of pond water. Foremost amongst the zooplankton are daphnia. These tiny crustaceans are essential to promoting clear water by filtering out, and consuming, suspended particles of algae. We need to look after them. This is the main reason an Organic Pool shouldn’t have fish – they eat the daphnia.

Algae will never disappear completely, after all they are wild plants and part of the healthy eco-system, but in a properly functioning pool most of the algae will be confined to the margins or hardly visible at all. In the Organic Pool, the area is divided into two sections, the swimming zone and the regeneration zone. The regeneration zone contains the plants so is also referred to as the planted zone. The pool has the deep swimming zone in the middle surrounded by the planted zone. The planted zone should represent at least half of the total area of the pool, and it is here that most of the water conditioning occurs.

The water is circulated throughout the whole pool. If a pool is large enough, with enough deep areas, then it can rely upon natural convection currents and surface wind movement to maintain the water circulation. If the pool is smaller, or the regeneration zone proportion of the whole is reduced below half, then technical equipment can provide the circulation and filtration. Conventional chorine pools can expect a build-up of chemical residues, so the pool needs to be drained out and the water changed from time to time. The water in an organic pool, on the other hand, never needs to be changed because it is constantly being maintained by the pool’s ecology. This equates to a huge saving in precious water resources.

Because tap water contains chemicals that interfere with how a natural pond works, it is better to fill your pool with rainwater. All the rainwater that falls on our house is collected and pumped to the pool. Even better, it is quite simple to construct devices to divert the first flush of roof water away, reducing the amount of detritus making its way into the pool. It may still take many weeks or months to fill the pool, but if you are making the pool yourself, you will find that it fills up as you are working on the project.

The laboratory water tests for my organic pool showed, not only was it perfectly safe for swimming, it was good enough to drink. It comfortably exceeded drinking water standards in all parameters tested. ■

David Pagan Butler has written “Organic Pools DIY Manual” and produced the film “Natural Swimming Pools – a guide to building your own” which has inspired self-builders across the globe. Have a look at facebook/organicpools to see many other examples. He also runs courses for anyone interested in building their own Organic Pool. To talk pond stuff and drink loads of tea, log on to

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