GRUNDFOS Pump Genie 

The Grundfos Pump Genie is an interconnect device that enable the connection of 2 different water supplies to the one pump unit. The Pump Genie will always give preference to the rain-water tank and will automatically change to town water when rain tank supplies become low. One advantage of the water Genie over other types of switches which are available is that it never allows the two supplies of water to combine. It can be fiited to a new CH2or CH4 series Press control pump at the time of installation or at some later date