Often seen in Europe, natural swimming pools are beginning to see some popularity in the United States. The newly introduced pool concept is populating a buzz within the pool industry increasing curiosity for home owners. To put some questions to rest, we’ve put together some information detailing how “Natural Pools” work.
Natural Swimming pools are a bit different than the pools you’re probably used to. Traditionally pools in the U.S. are made with fiberglass, vinyl or concrete/gunite. Natural pools still use some form of concrete to maintain the strength and integrity of the pool, but do so with a combination of materials working together in a much different way.
Unlike traditional pools, natural swimming pools don’t use a solid shell throughout. Instead, a combination of solid construction, compacted soil and liners form the seal and backbone of the pool. The construction is comprised of two tiers. A “swim area”, which is dug out and surrounded by a block or stone wall, back-filled with concrete and compacted soil. Outside of this area, sits the regeneration zone or plant area, made for plant growth. This area is also surrounded by a block or stone wall, but is much smaller in height. This area sits higher on the ground plane, and forms a shallow area in which the plant life can thrive.
The pool bottom and sides are covered with a strong liner or packed with Bentonite Clay which prevents water from seeping into the ground. The clay or liner covers the sides and bottom, while creating a seal for the pool. On either side of the pool sits the shallow regeneration zone. The zone contains about 4 to 5 inches of gravel or pea rock on top of the clay or liner foundation. The regeneration zone is contained by the outer block/stone wall of the swimming area or a wood retaining wall that lies on top of the outer wall of the swimming area.
To help circulate filtered water, aerate and prevent stagnant water, a small pump is installed to move water through aggregate on the bottom of the regeneration zone and back into the swimming area of the pool.
So How Does This Work?
Natural swimming pools work much like natural ponds or lakes. Water filters naturally through the micro-organisms in plant life. They not only help filter the water, but keep a balanced ecosystem in the pool. In short, the plants in the regeneration zone (plant area) in the outer, shallow parts of the pool compete for the same nutrients that algae needs to grow. This process prevents algae growth and filters your water naturally. The water in the regeneration zone is then circulated through aggregate, further filtering the water and returning it to the swimming area using a small pump.