When the building of a pool comes up in discussion, the question of kind usually boils down to binaries like indoor versus outdoor, above ground versus inground. But a recent trend making waves, so to speak, concerns the very nature in which pools are made and the way they are operated. An increasingly popular kind of swimming hole, in both the public and private spheres, is the natural swimming pool.

While requiring a greater initial investment, such pools need much less maintenance than ones using traditional filtration. Popular in Europe for decades, the American public was first exposed to a natural swimming pool in 2015, when Webber Park in Minneapolis opened the first of its kind in North America.

What is a natural swimming pool? It's actually two pools, or one pool that is bifurcated into an accessible area and an inaccessible area: the swimming pool, built with traditional materials like concrete or vinyl, and the regeneration pool or zone, which acts as the filtration system. Instead of using chemicals like chlorine to keep the water clean, the regeneration zone typically uses the roots of water-based plants (or, alternatively, a layer of gravel) as a filter.

Besides being more environmentally friendly than pools that require chemical filtration, they are much cheaper to maintain.

According to a February piece in The Spruce, a home interest website, “Organic or natural pools require much less maintenance than a conventional pool, and their year-to-year costs are lower after construction is finished. They don't require chlorine, chemical filtration, pH balancing, or any of the other side costs and numerous daily and weekly chores that go with keeping a normal pool clean.”

But the flip side is that a natural swimming pool requires a much more substantial initial investment than a traditional pool would — the regeneration zone, for instance, needs to be of equivalent size to the swimming pool proper for effective filtration. This also creates another challenge when considering space and size. Others may be put off by the idea of swimming near plants or in water that isn't the crystalline blue most are accustomed to.

Still, given the maintenance figures that municipalities have to eat every year, sometimes leaving the income/expense balance sheet in the red, perhaps more communities with designs on building a new pool might start thinking green sooner than later.