Water shortages in London and the South East - are there any demand side factors?

We are told that we are in a state of drought due to the reduced rainfall over the last two winters but are there other factors that could affect the shortage of water. Shortage of water is a supply issue, how about demand and storage issues? How much has the population of London and the South East increased over the last 15 years? What effect does that population increase have on water consumption? Have any new reservoirs been built or other supply-side measures been built to cater for the increase in demand?

The BBC and others are happy to parrot the line that weather/climate change is to blame but are there not other factors?