Had a visit from a Yorkshire Water bloke yesterday to test the water quality in our area, and learnt a few things. Our supply comes from Langsett, apparently, so not too far away. What surprised me was that areas quite close to here get their water from York! It seems that they are not allowed to lay pipes under the M1, so those areas east of the motorway (such as Rotherham, Thorpe Hesley etc.) have to look elsewhere, and that elsewhere is near York. The water’s pumped to a huge underground tank “like a cathedral” (can’t remember where), up to a hill near Wentworth, then gravity fed to destinations.
I did ask him what that small reservoir up on Hallam Moors is used for, but he wasn’t even aware that it existed, so that must remain a mystery.