Water purifier with means for indicating when filter replacement is due and for automatically initiating a membrane washing step

摘要

A water purifier includes a replaceable pre-processing filter, a washable membrane, and a replaceable post-processing filter through which potable water is sequentially conducted. A controller determines a total use time of the filters and membrane and compares the total use time with a reference time for replacement of the filters and washing of the membrane. When the total use time for the filters has reached the reference time, visual and audio indicators are activated. When the total use time for the membrane has reached the reference time, a valve is actuated which permits potable water to flow across and clean the membrane and then be discharged to waste.