This from a water conservancy website (I'm repeating the data not confirming or endorsing it .....jeez I waorked as a council liaison officer for too long

)
"Water loss comes from two sources A UK government department puts losses through leakage of supply pipes (in England and Wales) @ 3.6 billion litres a day. According to The Independent a further 1.1bn is lost each day in Scotland. So... Through leakage in supply pipes 4.7billion litres are being lost each day..."
In 1976 (the hottest summer on record apparantly), whilst still a butcher one of our customers was an "aquiferic architect" (or something like that) he said plans had been drawn up at a cost of just under £2 billion, which would link every resovoir north, south, east & west with a fully fledged pumping system. Apparantly this would stop flooding and water shortages nationwide by shifting vast quantities of water at the touch of a button (well probably several buttons).