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A DIY natural pool

By April 14,2020 October 2nd, 2023 No Comments

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Building a DIY natural swimming pool can be as simple as building a traditional swimming pool. It can even be facilitated if you move away from concrete or prefabricated walls.  We explain the method at the end of this article.

How to design a natural pool

Choosing to build a natural swimming pool is a great adventure that must start with a reflection and an awarenesss. The fact is that its functioning is different from that of a traditional swimming pool.

Any form is acceptable. But, be careful, it must respect certain rules, in order to avoid dead zones, favorable to the development of algae. For a DIY project, a box shaped pool will be cheaper to build.
Since the water is treated without chlorine or other chemicals, the choice of  the location is very important. A somewhat sunny area is a good option but be careful to avoid spots that are too sunny to avoid the proliferation of algae.
In natural pools, the pool edges are forgotten in favor of fairly informal edges, even on a gentle slope, largely using rocks and grass. There are also dead ends on the beaches covered with stones or tiles. We prefer a material such as wood, and, why not, we will do without the beach. Are there any around lakes and ponds?

The natural pool filtration system

You can install a natural filtration by lagooning or use biological filtration that will occupy less space in the garden. In both cases, it will be a natural swimming pool, since it is devoid of any chemical product.

Lagoon filtration

It is inspired by the ecosystem that governs lakes and ponds and uses the purifying and oxygenating properties of plants. Add to that the filtering power of a porous volcanic rock, the pozzolan.

The swimming pool  is made up of 2 distinct zones:

  • The swimming space.
  • The lagoon area or regeneration area: with an area more or less equal to that of the swimming pool, this is the area for purifying water from the swimming pool. Aquatic plants, algae and microorganisms provide oxygenation and water treatment. In short, it ensures the quality of the water.

It is possible, even desirable, to install a fine prefilter between the swimming pool and the regeneration zone: its role consists in retaining organic waste such as hair, sun products, pollens, dead leaves, etc.

To better oxygenate bathing water, we often use a waterfall or aerators that will stir the water.
Bathing water passes by gravity (overflow) or by suction in the lagoon area. It enters it by pushing back into the bottom of the basin and is filtered by the pozzolan. It then crosses the ecosystem of plants, bacteria but also aquatic fauna which will develop over time. The water returns to the swimming pool, either by cascading overflow from the lagoon, or pushed by a pump.
This filtration requires a good knowledge of plants and regular maintenance to maintain a high-performance ecosystem. It also requires sufficient space for the 2 basins; reducing regeneration space would interfere with water treatment.

Biological filtration

This is the other solution for a natural swimming pool in self-construction; the lagoon is replaced by filtration based on the ability of bacteria to digest organic waste present in the pool water. From the outside, you won’t see the difference with a traditional pool.
There are different systems but the basic principle is always the same.
The water circulation is like in a traditional swimming pool; the pool water is sucked by the pump through the skimmers or in the buffer tank for infinity pools. This post only talks about the filtration of the swimming pool.
At the outlet of the pump, the water goes through the following stages:
It passes through a pre-filter with a vortex effect which will allow the heaviest waste to settle. This filter can be replaced by a screening system in skimmers.
Then it passes through a biological filter, the filter medium of which has been seeded with bacteria. The biofilm created prevents even the finest waste from passing through.
An UltraViolet radiation lamp system then ensures its disinfection. The bactericidal, virucidal and algicidal properties of UVC rays are used.
Finally, an injection of minerals and bacteria keeps the water in balance and controls the pH.
Filtered and treated, the water then returns to the pool through the fittings.

Transformation of an existing pool

This form of self-construction of a natural swimming pool is the simplest; you are indeed starting from an existing basin. It is quite easy to replace your conventional filtration with biological filtration and thus enjoy the pleasure of swimming without chemicals and chlorine.

A DIY natural swimming pool

A natural bathing  is much simpler to build than a concrete pool and will benefit from tax or security system exemptions that the law provides for swimming pools in many countries. The first step is to carry out the earthwork to the desired shapes and depths.

natural pool

A DIY natural pool

It is preferable to choose a clay zone to ensure a natural seal. If this is not possible, the use of EPDM, synthetic rubber lining membrane,  or the concreteite, a moisture absorbing clay, will ensure the perfect waterproofing of the bathing. In the regeneration zone, a layer of pozzolan, a porous volcanic stone with high filtering power, is spread out at the bottom.


After installing the pump, all that remains is to fill it with drilling water or rainwater. The creation of the lagoon basin ecosystem will be done little by little; it begins with the establishment of oxygenating and purifying aquatic plants and continues with the progressive installation of bacteria and fauna.

Here too, lagoon filtration can be replaced by biological filtration. The design of natural swimming will therefore be facilitated.

Although this “construction” technique has advantages such as price or ease of implementation, the rustic appearance is off-putting to some people.

In conclusion

The term “natural swimming pool” therefore seems a bit overused to me and everyone implies what they want. The main thing is that the client is happy with the result. If you want to engage in a DIY natural swimming pool project, you must have perfectly clear ideas about your goal and the constraints of each technique

It is however obvious that the construction techniques, the shapes of the pool or the landscaped appearance do not qualify a swimming pool as “natural”. The filtration system as well as the water treatment play a crucial role! As an example we offer the photo of 2 swimming pools: one is landscaped, the other natural. Do you see the difference?

This is a popular article to help you realize that the term “natural pool” is a large catch-all in which everyone puts what they want. The fact remains that the aim of companies is to sell their structure, their equipment or their patent and like everything that fits into the “organic” or “natural” box the cost is increased. If you have such a project and you find it hard to see clearly, contact us; we do not sell materials, structures, … but we offer ideas and advice!

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