Would you like a completely private outdoor pool in the garden with clear water and above all without any chemicals? Then a natural pool with its clear architecture and water purification on a biological basis might be the right choice. But what is a natural pool and how is it possible to produce naturally clean water without aquatic plants and disinfectants?

Differences natural pool and swimming pond

In addition to a swimming pond and swimming pool, a third variant for the garden has established itself in recent years: the natural pool or biopool. It offers a perfect opportunity to combine chemical-free bathing pleasure with a small footprint and high design standards. Whether you build a swimming pond or rather a natural pool depends not only on personal needs, but also on individual wishes and ideas. In order to make a decision, you should first know the differences as well as the advantages and disadvantages of both variants. The biggest differences lie in the technology of water purification. In contrast to the classic swimming pool, only biological-mechanical cleaning is used in the swimming pond and natural pool .

swimming pond

  • usable swimming zone: about 50% of the total area
  • Shape: curved, individual design possible (more like a garden pond)
  • relatively high maintenance costs
  • Flora and fauna: numerous plants and animals in healthy biotopes
  • Technology for comfort: no heating or massage jets possible
  • Predictability: Algae growth, temperature and many other processes can hardly be predicted

natural pool

  • usable swimming zone: around 85% of the total area
  • Shape: clear lines (like in a classic swimming pool)
  • Flora and fauna: only microorganisms, otherwise no plants and animals
  • little maintenance (a pool robot takes care of cleaning)
  • technical accessories: all refinements such as a counter-current system, heating and much more are possible

At first glance, the differences may not seem particularly large. However, if you go into detail, these quickly become the decisive factor for the selection. Because of the larger usable area, a natural pool is better suited for smaller gardens. If you value technical refinements and comfort, you can usually not achieve this in a swimming pond because of the sensitive fauna and flora.


In contrast to a swimming pool or a swimming pond, a natural pool generally consists of two basins:

  • a large swimming pool
  • a water treatment tank (biological and mechanical cleaning)

The basin for cleaning the water usually consists of a technical system. In large gardens, a plant basin for water treatment is also conceivable, which can consist more or less of a normal garden pond. A powerful pump conveys the water from the pool to the separate area where biological treatment takes place. The cleaned water is then returned to the original pool.

Basic instructions for self-construction

If you decide to build a natural pool yourself, you have to plan it well in advance. In our basic instructions you will therefore find the most important key data for self-construction.

preliminary considerations

A number of factors are important for a successful and smoothly functioning natural pool. This includes not only the size, but also other factors, the details of which you should know and check very well.

  • space
  • location
  • soil condition
  • terrain features
  • Technology (type and dimensions)
  • Connection and power options

Do-it-yourself – even after good basic instructions – should therefore not be underestimated. The layperson is often completely overwhelmed with the necessary excavation and installation of the technology on their own. In many cases it makes more sense to contact an experienced pool builder.

location and space

An area of ​​around 30 square meters is enough to cool off in the biopool. On larger properties, a pool with a water surface of 70 square meters is considered a good average. In addition, space is required for the connected cleaning basin. When choosing a location, pay attention to the solar radiation. The less direct sunlight falls on the pool, the lower the risk of unwanted thread algae forming. In order not to contaminate the water unnecessarily, it makes sense not to build the pool directly under trees.

Tip: In order to check whether the desired size of the pool is feasible, you should lay out a rope on site and draw up a true-to-scale sketch including the technology.

construction and material

The smooth functioning of a natural pool is geared towards the fact that there is a lack of nutrients in the water. That’s why you have to pay attention to the right choice of materials when building your own. Only use construction methods and materials that meet these requirements and under no circumstances encourage algae growth. Since the smallest bumps are disruptive, both the floor and the walls must be very flat. A pure foil construction like the swimming pond is not suitable for a natural pool. Because of the special cleaning conditions, the walls and floor must be flat and very stable. Smooth surfaces reduce algae growth and make it easier to clean the natural pool.

1. Concrete or masonry construction

The most common construction for a natural pool is the wall or concrete construction. First, a concrete floor slab is poured onto the ground in the pit. Whether the walls are made of concrete or a wall is raised is a matter of taste. Another seal is then applied to the inside, which also has a smooth surface. This prevents algae and other microorganisms from settling in the small cavities and preventing the water from escaping. Various materials are suitable for this seal:

  • ceramic tiles
  • natural stone
  • waterproof plaster
  • Polypropylene foil (must be welded)
  • special resins (plastics) for painting

2. Prefabricated pool

These pools are manufactured in the desired dimensions directly by the manufacturer according to your wishes and are therefore also referred to as prefabricated pools. They usually consist of welded polypropylene plates or cast in one piece and then transported to your home. However, this is only possible up to a certain size.

Note: When building your pool yourself, make sure that you use environmentally friendly materials. Epoxy resins and plastics, which emit toxic substances, are still used for sealing and plastic pools in particular.


The earthworks to excavate the pit for the pool are a major expense in construction. Large amounts of earth have to be moved. For such profound excavation work as with a natural pool, mini excavators, which you can rent by the day, are worthwhile. Already during the excavation work, gradually remove the garden soil. You don’t need a lot of soil to fill up the sides. However, large mounds of earth are very cumbersome, especially in smaller gardens. In addition, the question arises as to whether you can get the excavator onto your property at all and how you regulate the removal of the excavated material.


It is best to plan for all possible eventualities from the outset. This also includes protection against overflowing in heavy rain. To do this, you can either create drainage around the biopool or install an overflow on one side that leads into the sewage system or into a rainwater tank. With the latter method, you not only prevent flooding in the beds or on the terrace, but also secure rainwater for watering the rest of the garden.


A pool is always a potential source of danger for children and pets. It is therefore not only necessary, but also legally obligatory to make a natural pool safe for traffic. For this reason, you should plan for the following things:

  • Fence, net or foil cover
  • decouple live parts from the water circuit
  • Minimum distance for electrical connections to the pond: 2 m

building permit

Depending on the federal state, the regulations for building a pool in the garden are different. It is therefore not possible to say in general whether you need a building permit or not. As a rule, a pool with a water content of up to 100 cubic meters can be realized without a building permit. In any case, ask your responsible building authority to be on the safe side.

Technology for water treatment

If you want to save space, it makes sense to install a compact, powerful filter system. This sucks plant remains and sludge from the bottom and the surface of the swimming pool and initially catches them in a coarse dirt separator. There are also systems that biologically break down the coarse dirt in the filter. The pumps should run as continuously as possible or at least at intervals of up to six hours a day, because only then will the bacteria in the filter system have enough oxygen to break them down and the cleaning process will be optimal. A rough guide to the space required by the filter system is around 15% of the area in the swimming area. In addition to the filter system itself, you will need:

  • Skimmer (sucks debris from the surface)
  • Suction/vacuum robot for the sludge on the bottom
  • possibly an automatic water refill

The technology for the pool can easily be installed in a separate chamber that is hidden under a walk-on wooden deck. When building your own, do not forget to install one or more service flaps so that you can easily access the technology at any time. The technical unit usually contains a small sand filter and a phosphate filter. The sand filter is flown through around the clock if possible. A biofilm forms on the surface of the sand grains, which breaks down dirt and ensures the biological balance in the pool. Phosphate is broken down in the phosphate filter. If aquatic plants are to contribute to cleaning in the facility, please consider that only a limited number of species can cope with the relatively nutrient-poor water.

Tip: Have the drinking water that you use for the biopool tested for phosphate in advance. In fact, phosphates are the main cause of excessive algae growth.


Of course, a water basin alone does not make a wellness oasis in the garden. With a natural pool, in contrast to a swimming pond, you hardly have to do without an equipment variant that you need to feel good. These include, for example:

  • pool heating
  • counter-current system
  • underwater lighting
  • massage jets
  • Jetty or stairs for boarding

To ensure that the biopool blends particularly harmoniously into your garden ambience, you have the choice between a wide variety of materials for cladding the edge of the pool – from sandstone to granite and wood.


Of course, the costs for your own natural pool in the garden depend on the technology and the material used. Basically, you should expect at least 150 to 400 euros per square meter when building your own. For a natural pool with an area of ​​around 50 square meters plus the necessary filter area, that would be between 9,000 and 24,000 euros. There are hardly any upper limits, depending on which special equipment and accessories are to be installed.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *