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 awareness. 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, 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 crucial. A somewhat sunny area is a suitable 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 various filtration systems

You can install a plant-based filtration system 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.

Plant-based filtration system

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.

Piscine naturelle autoconstruction
Plant-based filtration system

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 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 plants are replaced by microorganisms. The system involves harnessing the natural capabilities of living organisms, such as bacteria and microorganisms, to break down organic matter and remove impurities from the 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 talks about the filtration of the swimming pool.

Biological filtration

At the outlet of the pump, the water goes through the following stages:

  • It passes through a pre-filter with a vortex effect, which allows 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 return inlets.

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Find out about the benefits and constraints

The idea of swimming in a natural pool is very appealing. Nevertheless, you must select an appropriate system based on your expectations and the availability of maintenance that may be time-consuming.

Consider the climate conditions

In warmer climates, the higher temperatures can make the maintenance of a natural swimming pool more challenging. For plant-based pools, this is particularly true.


Advice on designing a natural swimming pool ?

The different ways to build

The natural pool, like a pond

This kind of natural pool 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.

It is preferable to choose a clay zone to ensure a natural seal. If this is not possible, the use of EPDM, a synthetic rubber lining membrane, or the bentonite, 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, plant-based 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

Submerged wooden pool structure

These pools first appeared on the market twenty years ago, and have gone from strength to strength since then. The external appearance of the pool is that of a wooden pool. An EPDM membrane is placed between the ground and the wood structure; this membrane ensures pool water tightness. Wood is a natural and renewable material, making it an environmentally friendly choice.

Note: The submerged wooden pool should not be confused with the wooden pool with a liner inside.

The transformation of an existing pool

Starting with an existing pool, you can easily replace your conventional filtration system with biological filtration. Although your pool will not qualify as a natural swimming pool, you will have the pleasure of swimming without the presence of chlorine or other chemicals.


The term “natural swimming pool” therefore seems a bit overused and everyone implies what they want. In the end, the most important thing is that the customer is satisfied with the result. To embark on a self-built natural pool project, you must be crystal clear about your objectives and the constraints associated with each technique. Do you want a natural pool or a landscaped pool?  

No pool can, of course, be considered “natural” in terms of construction techniques, pool shape, or landscaping. The filtration system and water treatment system play a critical role.

In this article, we hope to help you understand how the term “natural swimming pool” is a catch-all term that applies to a wide range of activities. Nevertheless, the aim of the companies remains to sell their structures, equipment, or patents, and as with anything labeled “organic” or “natural” the price increases. Having difficulty figuring out such a project? We do not sell equipment, structures, etc., but we can provide you with ideas and advice.