To provide a method and a device of detecting water passage abnormality in a filter in which the water passage abnormality due to clogging in a filter can be surely distinguished from that caused by an other cause than the clogging and which is simple in the construction and low in the cost.
In this method of detecting water passage abnormality, when a flow rate switch 6 detects that the quantity of water passing through a filter 4 installed in a water channel is lowered to a set value or less, based on the detection signal of the flow rate switch 6, a control part increases the discharge pressure of a pump 7 installed in a channel by a prescribed pressure. When the flow rate switch 6 detects that the quantity of water is increased to a set value or more within a fixed time after that, the switch 6 judges that water passage abnormality due to clogging in the filter 4 is caused and warns that water passage abnormality due to the clogging in the filter 4 is occurred.
ENDO TEN
KAMOGAWA HITOSHI
