our system is set up so that the kitchen tap and downstairs loo are first off the system then the water softener then the main goes upstairs to the attic tank. The softener is installed so that its in the line after the kitchen water so only softens the upstairs cold and all the hot. That's how a softener "should" be installed. When the installer came. he checked our system and found that our house was set up backwards, ie the mains water went upstairs first then to the kitchen. The plumber lifted a floorboard upstairs and installed a crossover pipe which reversed the order of where the water went...simples.