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Natural Swimming Pools

Natural Swimming Pools – Part One

We’ve all become familiar with the basic tenets of pool maintenance. Skim daily. Brush and vacuum regularly. And for goodness sake, maintain a healthy chlorine level. Whether you use a salt water generator, an automatic chlorinator, or just good old fashioned liquid chlorine, your pool absolutely needs chlorine. Green hair? Red eyes? That “clean pool” smell? It’s all par for the course. Or is it? Since the 1980s, a small but growing movement has been making waves (excuse the pun) in the swimming pool industry. What if you could keep a pool clean with absolutely no added chemicals? What if you could bathe in crystal clear water that is so natural you could drink it? Natural swimming pools make just that promise. But what are these unusual pools and how do they work? Here is the first part of our two-part series on natural pools.

Natural Swimming Pools - Part One [infographic]

The Promise of Natural Swimming Pools

A traditional swimming pool should ideally be “dead”. That means that the water is treated in such a way that nothing can grow in it. The chemicals that are added to the pool make it inhospitable to natural life, most importantly algae. To keep a traditional swimming pool clean, you need to constantly add sterilizing chemicals. In nature, standing water would quickly become host to a large number of plants and animals, from algae to tadpoles and mosquitoes. Keeping a traditional swimming pool clean means constantly battling nature to keep the pool completely free of natural life. It is the only way to avoid harmful algae and bacteria that would make swimming in the water unpleasant at best, and potentially unsafe.

A natural pool seeks to do just the opposite. It does not use any chlorine, man-made materials, or mechanical means to sterilize the water. The water in a natural swimming pool is alive in the sense that it is far from inhospitable to life. In fact, the water is so pure that you could fill a glass and drink it. But just because it is alive, a natural swimming pool isn’t necessarily full of life. Instead, a natural swimming pool can be crystal clear. The magic happens in a separate but attached area called the “regeneration zone”, where the water is cleaned.

The regeneration zone uses the same principles as nature to clean the water from the swimming pool. Carefully selected plants, as well as aerobic and anaerobic bacteria,  break down harmful microorganisms. To further clean the water, it passes through a biological filter filled with just the right bacteria. All together, these carefully selected living organisms filter out the undesirable stuff so well that when the water is circulated back into the swimming area, it is completely clean.

The History of Natural Swimming Pools

The concept of natural swimming pools has roots in aquaculture, natural living, and traditional pool design. The first natural swimming pool was built by Werner Gamerith, an Austrian professor, in the 1980s. Gamerith is well-known in his home country as a cultural engineer and water manager, environmental and anti-nuclear activist, author, and photographer. He built the pool, which he called a schwimmteiche, or swimming pond, in his own garden. He went on to lead the early movement to build more natural swimming pools around Europe.

During the late 1980s, the natural swimming pool movement grew in Austria. It then spread into Germany and neighboring countries. Eventually, the idea spread into other parts of Europe, including the U.K. More recently, the movement has picked up steam with builders and natural swimming pool organizations in Australia, New Zealand, and the U.S.

The center of the movement remains in Austria and Germany. Germany is home to The International Organization for Natural Bathing Water (IOB) , which calls itself an umbrella organization of swimming pond experts. Founded in 2009, it currently includes 14 national organizations and over 600 individual pool builders in 23 countries.

Natural Swimming Pools are relatively new in the U.S., though their popularity has seen steady growth. The first (and currently only) public natural swimming pool in North America was completed in 2015 at Webber Park in North Minneapolis. It was the culmination of a 10-year, $6 million project and can accomodate 500 bathers.

In Europe, natural swimming pools are much more popular. Estimates put the number of public and private natural swimming pools in Europe at about 20,000. The first public natural swimming pool in Europe opened in 1998 in Germany. Since then, over 100 public natural swimming pools have been installed in Germany alone.

Types of Natural Swimming Pools

Natural swimming pools are defined by their most startling characteristic, the lack of any man-made sterilizing chemicals to keep the pool clean. But within that definition, there are several different variations on the concept of the natural swimming pool.

The most natural type of natural swimming pool, often referred to as a swimming pond, is a “one-pot” design. It has a single large body of water that includes the swimming area and the regeneration zone. A regeneration zone, basically a carefully curated artificial wetland, covers roughly half of the pool, often around the edges or one side. The rest of the pool is swimming space. Most one-pot swimming ponds are split equally between swimming space and regeneration space.

Another variation on natural swimming pool design, the “two-pot” design, is more similar to a traditional swimming pool. There are two areas, a swimming area and a regeneration zone, separated by a dividing wall. The wall extends to just below the surface of the water, so that water can pass between the areas, but the plants are kept in the regeneration zone. The plants in the regeneration zone–typically sedges, reeds, and rushes–are hydroponically grown over a special filter substrate. The plants, in combination with the natural filter below, act just like a natural wetland, purifying the water and removing bacteria and nutrients that could feed algae. In some cases, the regeneration area can actually be completely separate from the swimming area, connected only by pumps and plumbing.


Bio-pools, like natural swimming pools, use no man-made sterilizing chemicals. But unlike natural swimming pools, they also don’t use a regeneration zone. This allows for non-chlorinated pools in areas that are not large enough for both a pool and a regeneration zone. Instead of removing debris and the nutrients that algae feed on solely through the activity of a man-made water garden, bio-pools rely on a very special filter. This natural filter sieves out phosphates and other organic substance from the water, eliminating the need for harmful chemicals.

Coming Next Week…

We’ve touched on the principles of natural swimming pools here, as well as their history. Next week, we will take a more in-depth look at the mechanics of a natural swimming pool and how they are built and maintained. We’ll also look at the cost and other factors involved in installing your own natural swimming pool. (You can find Part Two here.)

In the meantime, we want to remind you that The Pool Butler is here for all of your (traditional) swimming pool needs. If you ever have a question about your swimming, need a repair , or just want help maintaining your pool , contact us . We’re a full-service swimming pool company, and our white glove service can’t be beat!

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