PURPOSE: A filtering system is provided to prevent water quality drop of the filtered water due to the filtration membrane damage and to secure the stability of the filtration work by detecting immediately and automatically the damage of the filtration membrane which can be generated among the filtration operation. CONSTITUTION: The filtering system includes: a module(100); a bubble detect device; an alarm; and a controller. The module comprises the filtration membrane. The bubble detect device detects bubble which is mixed to the filtered water which passes through the filtration membrane due to the damage of the filtration membrane. The controller receives the detection signal. The controller outputs the control signal for stopping the filtration work of the module. The detection signal is the signal detecting the bubble from the bubble detect device. The bubble detect device is the optical sensor.
