Over the past couple of years, natural swimming pools and ponds have gained a lot of attention. While there is some debate of the definition of natural swimming pool vs natural swimming pond, they are essentially the same thing. Basically, it’s a body of water isolated from normal ground water via a membrane whose water is filtered through natural elements such as gravel, rocks, and plants as opposed to being disinfected with chemicals such as chlorine.
Natural swimming pools were first introduced in Austria and Germany in the late 80’s and early 90’s. Since then, they’ve become very popular in Europe with over 20.000 existing and over 100 of those being public pools. Word spread to the American market in the 2000’s and NSP’s have been gaining momentum here in the states. The first public natural swimming pool is currently being built Webber Park in Minnesota which is expected to open in 2015.
The pools filtration works in stages. Traditionally, a natural pool consists of a swimming zone and a regeneration zone. The swimming zone usually looks like a normal swimming pool with a square or oval shape. The regeneration zone is often located next to close by the swimming area and consists of plants and rocks which filter the water biologically. The plants are key as they absorb many of the nutrients that would typically contribute to algae growth.
Because a natural swimming pool is filtered through biological means it takes some time before the pool finds it’s ‘balance’. Although you can usually swim in them immediately, the biological equilibrium can take two or three years.
It’s worth noting that just because the pool is built using natural elements, it does not mean there is less maintenance. Since the regeneration zone contains plants, a certain amount of attention will be needed to remove dead plants and prune existing ones. You still will need to keep your pool free from debris such as twigs and leaves, especially since leaves can decompose and create microorganisms that cause algae growth. Once a natural pool finds it’s balance, however, maintenance becomes much easier.
There are other factors that determine the feasibility of a natural pool such as geo-location and climate. For example, areas where water can reach an average temperature of 82 degrees might allow harmful bacteria which is resistant to natural filtering. Certain climates may also not support the types of plants that are used for natural pool filtering although gravel-filtering can sometimes be used in those cases.