Hartlepool and area draw their water from bore holes and have similar tds levels.
Someone also said that one of the estates has a Walker Crisp factory. They require soft water in the process of what ever they do in that factory. It has been hinted that the council filter water going to that industrial estate and return the waste water to the water supply.
I would imagine that window cleaners processing water would need to 'soften' it before r/o.