factories will resort to spring water for processing, on account of its greater purity as compared with river water. Not infrequently, pure water is obtained from springs in the neighbourhood of rivers or artesian wells, so that both kinds of water can be used together. River water, crude or cleared in a sedimentation tank, is used for washing the peeled roots; and spring water or artesian water, which needs little filtration, is used in contact with the flour in processing. If only river water is available, it may be used after sufficient purification.