The shed will be covering the exits from the house. In other words all pipework to and from the tank will exit the house straight into the shed.
However I will need to deal with the fresh water feed for the RO unit. The water source is about 20' away. I either have the RO unit at the water source and run the output of the RO unit to the shed or run the water source to the shed and have the RO unit in the shed. In both cases the pipework will need to be lagged.
Dave
