Connect it to the roof? Now I'm puzzled
Oh...
The village water supply arrives at the front of the house, through a water meter and is then routed to the garden taps, a tap in the kitchen (for fresh water) and to the cold tank on the roof.
From the cold tank it goes through a pressure pump to the cold taps and the hot water system (solar panels and storage tank).
So I have to interrupt the supply to the cold tank, route it to the ground where the water softener is, through that and back to the roof to connect to the cold tank.
Then, all the water in the house (taps, showers, washing machine, dishwasher, etc.) aprt from the drinking water tap in the kitchen... Which is actually a third-knob on the kitchen sink tap and is fed through a Reverse-Osmosis system!

Okay...?
So roof today to connect up loads of meters of net very flexible PVC water pipe...