We moved into a new house 6 years ago and have a water harvesting system (huge tank under the garden which takes rain from the roof and uses it to flush the loos, for garden hose etc). There is a gauge in the garage that tells you how full the tank is, and in dry weather we are now much more conscious of how much water we are using.
At the moment DH is busy emptying the garden water butts into the harvester tank as he thinks that the water butts overflowing is a waste!
Perhaps we all need to change our attitude to the way we use water.