WATER PURIFIER

To provide a water purifier comprising a backwash system which can reduce a cost and can avoid a risk of suspension of water supply.SOLUTION: A water purifier 1 comprises: a pipeline 23 in which raw water, which is supplied from a water source, is circulated; a flow rate detection part 16 which detects a flow rate of the raw water circulated in the pipeline 23; a filtration tank 31 having a filter material which captures impure components contained in the raw water; a storage part 42 in which a correction coefficient Dc is stored; and a control part 43 which calculates a maximum filtration water amount in which an amount of the impure components, which can be captured by the filter material, is divided by a concentration of the impure components contained in the raw water, an integration water amount of teh raw water circulated in a prescribed time which is measured by the flow rate detection part 16, a filtable water amount in which the integration water amount is subtracted from the maximum filtration water amount, and an actual filtration water amount of a date quantity such that an average of the integration water amount is calculated for every prescribed number of days, continues a filtration operation when the filtable water amount exceeds the actual filtration water amount of a date quantity which is divided by a prescribed correction coefficient, and transfers the filtration operation to a backwash operation when the filtable water amount falls below the actual filtration water amount of a date quantity which is divided by the correction coefficient.SELECTED DRAWING: Figure 2 【課題】コストの削減及び断水のリスク回避が可能な逆洗方式を備えた浄水装置を提供すること。【解決手段】浄水装置１は、水源から供給される原水が流通する配管２３と、配管２３を流通する原水の流量を検出する流量検出部１６と、原水に含まれる不純成分を捕捉するろ過材を有するろ過槽３１と、補正係数Ｄｃが記憶された記憶部４２と、ろ過材が捕捉可能な不純成分の量を原水に含まれる不純成分の濃度で除算した最大ろ過水量、流量検出部１６により計測される所定の時間で流通した原水の積算水量、最大ろ過水量から積算水量を減算したろ過可能水量、及び、所定の日数毎に積算水量の平均を算出した日量ろ過水量実績を算出し、ろ過可能水量が所定の補正係数により除した日量ろ過水量実績を上回った場合にろ過運転を継続し、ろ過可能水量が補正係数により除した日量ろ過水量実績を下回った場合は逆洗運転に移行する制御部４３と、を備える。【選択図】 図２