In each household, there is a pool or water tank that extends both inside and outside the home. Fresh spring water is continuously supplied to a basin, ensuring a constant availability of clean water. Residents use this tank to rinse pots and wash freshly harvested vegetables. However, if they dispose of food scraps into the water, they risk contaminating the entire village’s water supply. Fortunately, carp fish are adept at cleaning even the greasiest or most burnt pans, effectively handling the washing up in Satoyama villages. This traditional system, known as the riverside method, is widespread throughout Japan. After being purified by the carp, the water eventually flows back into the main channel.