machine 3 the tank 126 includes a water level indicator tube 132 which may be hydraulically isolated from the tank 126 by way of isolation valves 134a 134b for water quality monitoring purposes the indicator tube 132 is also hydraulically connected to a water testing tap 136 having a needle valve 138 tank 126 further has a fill port 140 for the addition of filtered and polished makeup water therein as well as a gate type drain valve 144 used during a general drain down of the apparatus 1 located downstream of the wash water holding tank 126 is solenoid operated valve 132 which controls the admission of wash water from the reservoir provided by the tank 126 into a single impeller self priming pump 146 for water testing purposes pump 146 is hydraulically connected to a water sampling tap 147 by way of ball valve 148 the output of the pump 148 is connected to the water inlet 6 of the washing machine 3 by way of a second ultraviolet sanitizer 149 flanked by union ball valves 150a 150b a ball check valve 154 another union ball valve 156 and a solenoid operated close off valve 159 this last valve 159 prevents water that may have been contaminated in the washing machine 3 from backing up from the machine 3 into the purified water present in the wash water holding tank 126 an additional pressure gauge 162 is provided upstream of the water inlet 6 of the washing machine 3 so that the pressure and hence the flow rate of recycled wash water can be monitored turning back to the wash water diverter conduit 94 and a description of the components therein a wash water interim holding tank 167 is connected to this conduit 94 upstream of.