Sabils were often constructed adjacent to mosques and were supported by waqfs, or charitable endowments. In Cairo, once a year when the River Nile was in flood, the water was transported from the river to the sabil, and carried in animal skins on the backs of camels or mules. The water was then brought to a stone basin on the ground-floor from which the attendant scooped cupfuls for all those who were thirsty. In some sabils the water from the cistern fed a fountain which emptied into a basin.