The average backyard pool is an inviting but oddly unnatural thing: a rectangular hole filled with water, in which nothing grows thanks to a regular infusion of chemicals. It's a far cry from the swimming holes of old. But a new wave of green pools (also known as natural swimming pools) is changing all that, bringing the experience of backyard swimming a little closer to nature, and transforming the private swimming pool into a much more environmentally friendly prospect.
The fundamental difference between a green pool and a run-of-the-mill swimming pool lies in how it's filtered. In a green pool, a pump circulates the water through either a gravel filter or a plant filter, which keeps the water clean without the need for chemicals. Natural pools don't have to be 'dirty', although they're often styled to look more like ponds and less like typical swimming pools.
Mother Earth News advises that, in order to keep the water in a green pool clean without the need for additional sterilization, the pool needs to be pretty evenly split between plantings and swimming area. Low walls, a few inches below the surface of the water, keep the plants separate from the swimming part of the pool.
While some natural swimming pools look almost identical to traditional swimming pools (except for the plantings), they can also be dug to look a lot more like ponds, with the planting/gravel area merging into the surrounding landscape.
Natural swimming pools are currently a lot more common in Europe than they are are over here, but they're beginning to catch on Stateside. The pool pictured above, which stays clean thanks to a pump and a filter of pebbles, is, believe it or not, located in Brooklyn.
Want to learn more about green pools? Mother Earth News has a quite comprehensive article on constructing your own natural swimming pool, or you can do a Google search for a company in your area that specializes in natural swimming pools. Biotorp, which is based in Austria, has been making green pools since 1986, and has plenty of inspiring examples on their website.