In each household, there is a pool or water tank that extends both inside and outside the home’s walls. A constant flow of spring water is directed into a basin, ensuring a steady supply of fresh water. Residents use the tank to rinse pots and wash freshly harvested vegetables. If they were to dispose of food scraps in the water, it could contaminate the entire village’s supply. However, carp are able to clean even the greasiest or most burnt pans, effectively handling the washing up in Satoyama villages. This age-old system is known as the riverside method and is practiced throughout Japan. Once cleaned by the carp, the water from the tank eventually returns to the main channel.