Abstract
This paper has reported on the risk of shutdown of water purification plant caused by Tsunami of Tohnankai Nankai eearthquake. First, the impact of Tsunami surge cause the deterioration of raw water quality was considered in the operation process of water purification. Second, an influence of shutdown of rapid sand filter process, and granular activated carbon absorption process was presented by using an experimental research. Finally, a strategical water treatment operation was discussed referring to the concept of Business Continuity Plan.