Natural swimming pool
A natural swimming pool, also called eco pool or chemical-free pool, is a type of swimming pool that operates without an array of sanitation chemicals and that can be built with a minimum of materials. Common in Europe, this swimming pool type leans toward an ethos of building with nature and blending into the natural landscape around it and thus may use gravel stone and clay instead of concrete or fiberglass, and aquatic plants in a filtration area instead of chemicals and mechanically-complex filtration systems for pool sanitation.