The water purification system for flow-coupled installation with a tap water inflow for producing a relatively purified water outflow includes a purification unit having a tap water inlet port for receiving tap water inflow and a purified water outlet port for dispensing purified water outflow from said purification unit. Using previously entered flow rate information, the meter establishes quantities of flow during each pumping cycle or totals for predetermined time intervals such as days or weeks. Thus, the number of pixels in the pixel portions is decreased, and transfer time of the control signal becomes short. The condition determining unit determines \u201cthe imaging condition of the main scan\u201d or \u201cthe condition of the correction processing\u201d, based on an execution result of the calibration scan.