Natural ponds and natural swimming pools

Say goodbye to chlorine and hello to beauty, by using plants for filtration and oxygenation of natural swimming pools.

Natural backyard swimming pool (NSP)
Natural swimming pool image via

The origins of natural swimming pools

Inspired by the beauty and joy of swimming in mountain lakes, a team of Austrian researchers are credited with launching a movement back in the 1980's that saw chlorinated swimming pools being replaced by natural swimming pools.

The idea of swimming in a pool that invited nature in rather than shutting it out with chemicals gained popularity rapidly, spreading first to Germany and then throughout Europe. Slow at first to take root in North America, natural pools are becoming more common here as well.

Why choose a natural swimming pool over a chlorinated pool?


Swimming in a chlorinated pool is refreshing and enjoyable on a hot day, but pales in comparison to the experience of swimming in a natural body of water. A swim in a natural pond does not leave you with itchy red eyes, dry skin or wanting a shower, which is common after swimming in chlorinated water.

In addition to providing a beautiful backyard aesthetic, natural pools have many other advantages, including:

  • excellent water quality;
  • chemical-free water treatment;
  • creating habitat for wildlife and flora;
  • reduced maintenance costs over conventional pools.

How a natural swimming pool operates:

Mimicking the biodiversity and function of the natural environment, natural swimming ponds have separate zones for swimming and water purification. Designs can vary, as well as the recommended sizes and ratios.

Minimum pool size recommendations range from 30 to 50 square meters, but we have also seen much smaller pools that function quite well.

Depending on design, swimming zones typically comprise 50 to 70% of the total water surface area; the rest is dedicated to filtration. Water is pumped to shallow areas with abundant plant life and aggregate that act as natural filters, keeping water pure and clear.

In order for plants to thrive, pH levels should be maintained between 5.5 and 7. If the pool is well-designed and located, it should require less maintenance than a conventional pool.

  • Surface area: The larger (and deeper) a pool is, the less likely it is to develop an algae problem. A minimum total area of 45 to 50 square meters is recommended for a healthy pool.
  • Depth: A deeper pool will mean a cooler water temperature, which might mean a slower start to your swimming season, but perhaps a more refreshing dip in the full heat of the summer. Somewhere between one and two meters will protect living organisms during winter, and in true Goldilocks fashion should be not too hot, not too cold, but just right.
  • Proportions of shade and sun: The sun promotes algae growth and photosynthesis, so really, the less exposure to sun the better. Sunny areas can be naturally shaded with floating leaves that will slow algae growth and protect aquatic life.
Natural swimming pond zone diagram
natural swimming pond zone diagram ©


Less mosquitoes, not more!

According to Mick Hilleary, pond specialist and founder of Total Habitat, moving water and the natural predators of mosquito larvae that will inhabit chlorine-free water will make natural swimming pools practically mosquito free.

In addition, having a natural swimming pond in your yard can actually work to reduce the population of stinging insects, by attracting dragonflies and other natural predators of fully developed mosquitoes.

Swim surrounded by wildlife

Plants, some insects, amphibians and other aquatic life are part of the ecosystem of a natural swimming pond. You end up sharing your swim with all the life (stationary and mobile) who keep your pool clean and clear.

This is very appealing to many, while others may at first be a little reticent. Keep in mind - these little creatures will have no interest in you and are likely quicker swimmers than you, so relax and enjoy.

  • Aquatic life - insects, snails and amphibians: they feed on each other, ensure healthy water and the charm of a natural pond.
  • Daphnia: These microscopic creatures are common in most lakes and ponds. They play an important role in regulating the cycles of nitrates, phosphates and phytoplankton. They are predators of bacteria and are an important source of food for other aquatic life.

Plants: Three kinds of plants typically regulate the natural cycle of swimming ponds:

  • 1) Floating plants: Water lilies and other floating plants rooted in the bottom provide shade and protect micro-organisms from UV rays.
  • 2) Oxygenating plants: By absorbing nitrates and phosphates, submerged and free floating plants contribute to the ecological balance of the pool and play an important role in slowing the growth of algae.
  • 3) Biological filters: As water passes through the fibrous root structure of plants, micro-organisms concentrated on the root system act as a natural filter, removing contaminants and excess nutrients from the water.

Fish or no fish

Introducing fish into your pool can be a very enticing concept, adding an entirely new dimension to the ecosystem, as well as your swimming experience. Keep in mind - including fish in your swimming pond will lead to fish excrement as well, which facilitates the growth of algae.

Additional maintenance is required with the inclusion of fish in your pond, so prepare yourself for that. For those willing to take on that additional challenge, we have found that the Pond Clinic in Ottawa, Ontario offers a good source of information on how to manage having finned swimming buddies.

Maintenance and winter preparation for natural pools 

Maintenance of a natural pool falls into a completely different category than that of a chlorinated pool. Caring for a natural environment makes pond maintenance more like gardening than the chemistry you would be performing with a conventional pool. Different ponds will require different levels of maintenance; what they all have in common in this northern climate is the need to prepare for winter. Do the following towards the end of the season while the leaves are still on the trees:

  • Prune plants and use a skimmer net to remove organic materials from the surface of the water. Cover the pond surface with a net to prevent the accumulation of leaves and debris
  • Dismantle and drain filtration systems and pumps.

Comparing cost - natural swimming pools vs. chlorinated pools

Some will tell you it costs more, some will tell you it costs less. What we deduce from that, is that the cost of a natural pool built by professionals will be roughly equivalent to that of a conventional in-ground pool. One great advantage natural pools have over chlorinated, is that no further landscaping is required as would be with a traditional in-ground pool, which can make the total finished cost of natural pools even more competitive.

Depending on the design and size, plan on spending between $40,000 and $70,000, give or take for either type.

Safety and municipal laws:

Like any swimming pool, natural pools can be a potential safety hazard and may be subject to municipal regulations. Before undertaking such a project, be sure to familiarize yourself with any legal responsibilities, as pools may require safety fencing depending on depth.

DIY natural swimming pools

For anyone that wants to try a DIY pond, the costs will of course be much lower. This will require some research, time and effort, but that can be time well spent. And this is time in your yard that you might otherwise have spent mowing grass, planting flowers or pulling weeds.

As is always the case with DIY projects, there are lots of videos available detailing many designs and construction methods where you can find inspiration. Be sure to settle on one that is suitable for your climate, in regards to pool depth and chosen plants. The following short video is but one variation that can help you visualize the concept and steps. Good luck, and let us know if you try it!

For further reading, we found the following sites quite helpful:

Images via



Natural swimming pool
Natural swimming pool