A natural swimming pool is constructed so water is clarified and treated by wetland plants rather than chemicals and UV lights. While Europeans have decades of experience with these pools, they are just starting to become popular in the United States. ESC has recently melded its decades of experience with created wetlands for urban runoff treatment with construction of traditional swimming pools and natural fish ponds, using natural Hill Country limestone for edges and waterfalls.
An example is this backyard pool, ten feet across and four feet deep, which is not for doing laps, but for sitting, cooling and observing. The pool is constructed with a concrete shell hidden by natural fitted limestone. A simple submersible pump pulls water from the deepest and shallowest areas and recirculates it 
through a series of three metal tanks that support wetland gardens. From there the filtered water is gravity fed to the fern wall and waterfall of the pond. The pond has been in continuous operation since its completion in fall 2015. All plants and fish in this wetland system are Texas natives. The success of this project offers proof that a natural pool can be designed correctly and attractively for Central Texas.
The owner says:
Here are a few reasons why we love our biofiltered pond:
It is beautiful
We love the water lilies, irises, frogfruit and other plants, and appreciate how natural it looks – it’s like having a spring in our back yard
It is peaceful
We enjoy the sound of the water, watching the fish and dragonflies, and listening to the frogs sing at night. It is wonderful to sit in the pond surrounded by native plants with fish swimming around and nibbling our toes
It is easy
We add some water occasionally from our rainwater collection tanks, and rarely have to add city water. Keeping the pump free of debris takes a couple of minutes about once a week in the summer and more rarely in the winter. It is much less work & less expense to maintain than a swimming pool and provides more enjoyment for us. We remove leaves, etc. on the surface of the water as needed with a little net or our hands while we are enjoying the pond. It doesn’t seem like work, but more like enjoying nature
We are amazed at how clear the water remains simply from the bio-filtration.
We haven’t added a single fish, amendment or product since the pond was installed, and it just looks better as time goes on