Bali traditional riceHistorical evidence indicates that since the 11th century, all peasants whose fields were fed by the same water course have belonged to a single Subak or irrigation cooperative. This is a traditional institution which regulates the construction and maintenance of waterworks, and the distribution of life-giving water that they supply. Such regulation is essential to efficient wet-rice cultivation on Bali, where water travels through very deep ravines and across countless terraces in its journey from the mountains to the sea.

The subak is responsible for coordinating the planting of seeds and the transplanting of seedlings so as to achieve optimal growing conditions, as well as for organizing ritual offerings and festivals at the subak temple. All members are called upon to participate in these activities, especially at feasts honoring the rice goddess Sri.

Subak cooperatives exist entirely apart from normal Balinese village institutions, and a single village's rice fields may fall under the jurisdiction of more than one subak, depending on local drainage patterns. The most important technical duties undertaken by the subak are the construction and maintenance of canals, tunnels, aqueducts, dams and water locks.