Natural swimming pools are cleaned through biological processes within the regeneration zone. The regeneration zone mimic a natural ecosystem, with plants, bacteria, and aquatic life that absorb nutrients and waste as food. Water is constantly circulating back and forth from the swimming zone to the regeneration zone, meaning there's a steady supply of freshly filtered water in order to swim in.
Traditional pools utilize harsh chemicals like chlorine to disinfect their water. This can be bad for the environment, and for your health. Instead, a natural pool creates conditions just as clean, without any of the harsh chemicals.