Residents of Dayan old town of Lijiang, Yunnan province, are washing vegetables and clothes by the Sanyan Well . [photo by Yang Qi/chinaculture.org]

The Sanyan Well has three pools in the exposed place of the spring. The three pools lie in different levels, from high to low. And the spring water flows down in order and form three layers, so it is also called Sandie Spring (triple-layer Spring) . It is a convention that the upper pool is used to drink, the middle one is to clean the vegetables and the lower one is to wash clothes. That is the efficient use of the water for the residents in the city. There are more than one such wells in the city.