Water quality monitor for a water purification system

Abstract

An improved water quality monitor is provided for use in a water purification system of the type having a reverse osmosis unit for producing relatively pure water from a tap water supply. The reverse osmosis unit supplies produced purified water to a reservoir for storage until dispensing, as by opening a faucet valve. An inlet shut-off valve closes to prevent tap water inflow to the reverse osmosis unit when the reservoir reaches a substantially filled condition. The water quality monitor includes electrodes in contact with the tap water and the produced purified water to obtain comparative conductivity readings which represent the performance level of the reverse osmosis unit in removing impurities from the tap water inflow. The monitor includes a test circuit responsive to movement of the inlet shut-off valve to take a conductivity reading at a point in time substantially after the shut-off valve opens to resume tap water inflow to the reverse osmosis unit, and substantially prior to shut-off valve closure when the reservoir reaches the filled condition. In one embodiment, the conductivity reading is triggered by the position of the inlet shut-off valve. In other embodiments, the conductivity reading is triggered in response to a float-mounted switch within the reservoir. In either case, the conductivity reading is stored in memory for subsequent periodic display, for example, each time the faucet valve is opened, by energization of one or more indicator lights.