Build Your Own Natural Swimming Hole

Image Gallery Illustration by Brad Anderson

Whether you like to practice your dolphin dives or lounge away the day on a raft, swimming is one of summer’s perfect pleasures. With a minimum of materials you can build an idyllic water oasis right in your own backyard and thwart summertime’s sultry dog days.

Although fairly common in Europe, natural swimming pools are in their infancy in the United States. Ask most American swimming-pool contractors to build a backyard pool and chances are they’ll roll out a long list of goods, including rebar, sprayed concrete, fiberglass and a complex filtration system. But in recent years, a few builders and a growing number of homeowners have learned how to build pools that look more natural and blend nicely into the landscape.

Natural swimming pools take a bit of forethought in their construction but can be well worth it in the end. Gravel, stone and clay are used in place of concrete or fiberglass, and aquatic plants and a simple aeration system is all that’s needed to keep the water clean.

In a natural pool, plants enrich the water with oxygen, support beneficial bacteria and other micro-organisms that consume debris, and give habitat to frogs, dragonflies and other water life. The result is a beautiful, ecologically diverse system that is relatively inexpensive to construct. A natural pool can be constructed for as little as $2,000 if you do it yourself, while conventional pools can cost tens of thousands of dollars. But the savings don’t end there. A natural swimming hole is fairly low-tech, and once established requires only a modicum of management. You won’t have to drain the pool each autumn and, except for topping it off now and then, you’ll fill the pool only once.

Dig it

The easiest and least costly way to build a swimming pool is simply to hollow a hole in the ground. You can make your pool as deep as you want, but the key is to make sure the sides slope, which will prevent cave-ins and offer easy entrance and exit. The ratio should be a 1-foot vertical drop for every 3 horizontal feet.

“It’s not a bathtub effect, but more like a soup bowl,” says Tom Zingaro, partner with Denver-based Blue Lotus Designs (www.BlueLotusDesigns.net), a pool- and pond-architecture company.

One of the main reasons traditional swimming pools are constructed with a steel framework is to ensure the walls stay vertical and perpendicular to the bottom surface of the pool. Construct a pool with sloping sides and you’ll eliminate the need for steel reinforcement.

Plants in your pool

Reserving at least 50 percent of your pool’s surface area for shallow plants, either at one end or in a ring around the sides, eliminates the need for conventional filtering systems. You’ll need to separate the swimming area of your pool and the filtration area, or plant zone, with a rim that comes to within an inch of the water’s surface. This rim keeps plants in their place but allows water from the swimming area to move to the plant zone for filtering. As water passes through the fibrous root structure of the plants, micro-organisms concentrated on the plants’ roots act as a biological filter, removing contaminants and excess nutrients from the water. Decomposer organisms, also found in the plants’ root zones, consume the bacteria, effectively eliminating underwater waste buildup.