The SpectraPure Flush Valve Kits are placed between the membrane reject port and the flow restrictor and provide a high flow by-pass to purge concentrated brine from the membrane housing, and rapidly flush any particulates from the membrane surface. The flushing is best done just before the RO system is shut down, by opening the Flush Valve Kits valve for 15-30 seconds and then turning the feed water source off.