How to estimate water usage?

Why are not all homes in the UK equipped with water usage meters?

• Some homes are unmetered and owners pay their water bills on a fixed monthly rate. However, unmetered bills removes the marginal cost for water consumption and this encourages people to use the water supply generously. To reduce water wastage, why is it not compulsory for all homes to be equipped with a water meter? "Currently, some 30 per cent of homes have a water meter and the figure is increasing by around 2per cent a year." - DailyMail.co.uk, 16 Aug 2007 "...people who have a meter use 10 percent less water than those on rateable value." - Cambridge Water Company

• Answer:

  Water meters are much more common in areas of the UK where water shortage is a problem, and where incentives are offered to go over to metering (i.e. the South East of England, mainly). Business likely to use a lot of water, like farms, are also often on metered supply, throughout the UK, as well. However, in large areas of the country, water supply outstrips demand in most years, and the biggest source of loss, is actually leakage. Partly, this is because it is very rainy, in the UK, and also because some social planning projects over estimated rates of growth. For instance, the water in the cup of tea, I'm drinking right now, came form the vast http://en.wikipedia.org/wiki/Kielder_Water reservoir, which far exceeds the needs of the region it supplies. There is very little incentive to push people in domestic houses towards metered use in these areas, because it is an upfront expense that may actually lead to a drop in revenues as people start to control the costs through their use of water.