There are a lot of differences between chlorinated pools and NSPs, but the biggest one is that these freshwater swimming ponds don’t require harsh chemicals to keep the water clean and healthy. “That said, the environment in a natural pool is not sterile like in a chemically treated pool,” Elniff says.

A natural pool uses a biological filter, plants, and pumps to clean the water. This system is kept in a separate area of the NSP called the regeneration zone, away from the swimming section. As Elniff explains, the biological filter is not a single piece of equipment that you hook up, like the sand filter for a traditional pool—it “needs to be built into the pool itself (or else into a connected pool or pond).” There’s typically a wall separating the swimming area from the regeneration zone, and behind this wall is where most of the aquatic plants and the plumbing system lie.

The plants and plumbing system in a NSP work symbiotically. The plants increase the oxygen level in the water and remove excess nutrients from it, while the plumbing (aka the jets) moves water low in oxygen from the bottom of the pool to the top so it can collect more.

The bio filter also is an extremely important part of the equation. “The biological filter you build into a natural pool, like our patent-pending method that is built into the rock walls of a pool and can even be built into the floor, needs to be robust and sized correctly for the size of the pool and its location,” she adds.

It takes all three of these elements combined to clean a natural pool, Elniff says. Aquatic plants or moving water alone wouldn’t be enough to do the job.

Benefits of Natural Swimming Pools

Possibly the best benefit of having a natural pool is being able to use it as a water feature all year. You likely won’t want to swim outdoors when it’s cold, but you can still appreciate an NSP as part of your landscaping since you don’t have to winterize and cover it the same way you do a regular pool. A natural pool can still freeze over, making it a potential mini ice skating rink or a beautiful water feature to look at.

Thanks to the lack of chemicals, NSPs also are safer for everybody, especially animals and children. If your dog loves the water but the chlorine bothers with their skin or eyes, a natural pool is an excellent alternative to a lake where they’ll surely get muddy. “Kids also benefit from natural pools in terms of nature education as well as use—we often include large beaches in our natural pools, which are great for little ones,” Elniff says.

Cons of Natural Swimming Pools

Because your natural swimming pool is also a living ecosystem, you need to run the pump year round, which can be seen as a con. “For this reason, we always recommend highly efficient variable speed pumps that can be turned down to a lower, more energy efficient setting over the winter months then back up to higher speeds over the spring and summer,” Elniff explains. While this does allow the bio-filter to continue turning over the water throughout the cold months, it can feel somewhat unnecessary to run your pool when you aren’t using it—but it really depends on your perspective of what a NSP adds to your yard.

Another con is the expense. Because of all the add-ons a NSP requires on top of the initial installation, the immediate cost of adding a natural pool is generally a bit higher than that of a typical, chlorinated in-ground swimming pool.

Installing a Natural Swimming Pool

As with any pool, the installation process depends on the natural swimming pool design you’re drawn to. Most of the installations Elniff’s company does resemble ponds, with bottom liners and walls built from rocks, more than they do chlorinated pools. However, it does have one model, the Midcentury Modern natural pool, that “is built more like a chlorinated pool at the start, with a concrete shell that is later topped with wooden walls, rocks, and plants,” she says. “This makes it sort of a hybrid-style build, so you can partner with a traditional pool builder in your area for the start of the build, then DIY the natural pool specific elements on top.”

Plants Used in Natural Swimming Pools

The selection of potential aquatic filtration plants is vast. According to UK company Poolscape, the water garden in a natural swimming pool should include: oxygenators, waterlilies, shallow and deep marginals, and waterside bog garden species. Look into the aquatic plants that are native to your area, and make sure you don’t choose any invasive species, just as you would when planning your backyard garden or landscaping.

Maintaining a Natural Swimming Pool

How you maintain a natural swimming pool changes over time, as the ecosystem develops. Generally, NSPs require more maintenance upfront as you create and grow the ecosystem, and later on, as the environment matures, its maintenance needs lessen. At the start, you need to supplement the water by adding more beneficial bacteria, essentially to jump-start the bio filter. Elniff compares it to a garden: “You first have to prepare the earth, plant the seeds, and wait for the plants to grow, helping them along with proper watering and sunlight. Then, once the plants are established and the garden is flourishing, you may only need to prune it here and there.” Establishing a natural swimming pool is much the same.

How Much Does a Natural Swimming Pool Cost?

Like any home project, the cost of an NSP depends on a few factors: style, location, and materials. “There are many different styles and construction methods, ranging from an underwater wood wall (what we call the ‘essential’ style natural pool) to stacked stone walls to a concrete shell like our Midcentury Modern natural pool,” Elniff says.

Location factors in mostly because it determines how accessible (and therefore expensive) certain materials are. Elniff says she’s seen the price of stone range from $30 per ton to $700 per ton from one location to another. “Because of these factors, natural pools range widely in price, anywhere from $15 to $300 per square foot, with most falling in the $20 to $80 per square foot range in our experience,” she explains.

Can I Convert a Chlorinated Pool to a Natural Swimming Pool?

Converting a chlorinated pool into a natural one is quite doable, Elniff assures us. The Natural Pool Academy is actually creating an online course about how to do it on a DIY basis. The difficulty of the conversion really depends on the size of your existing pool; turning it into a NSP will make it smaller since the bio filter needs space.