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We can see that public sector,electricity sector and agriculture are the main consumers of energy.
What is daily personal demand of water per liter for each person in England?
For a major water supply project there is a substantial time between the recognition of the need for water and the completion of the project (the lead time), so predictions of the future demand for water are essential and need to be made for around 25 years ahead. Prediction starts by looking at how the demand for water has varied in the past.
The diagram shows how abstractions varied between 1971 and 2001 in England and Wales. Although there is little difference in total abstractions for 1971 and 2001, there were large variations during this period, with a maximum of around 45 × 106 m3 per day in 1992, and a minimum of around 32 × 106 m3 per day in 1994.
Public water supplies in England and Wales generally increased between 1971 and 1990. Domestic consumption rose during this period due to population growth and the increasing domestic use of water per person. The fall since 1990 is due to:
• domestic metering,
• more efficient use of industrial water,
• periods of industrial recession, and
• reduced leakage.
The metered water supply in England and Wales rose gradually through the 1990s, and the unmetered supply fell, partly due to the increase in domestic metering.
Data have to be projected far into the future because of the long lead times necessary in planning for new water resources.
As well as looking at past trends, prediction of the future demand for water involves breaking down the total present demand into domestic, industrial and agricultural components, and identifying the economic, social and population factors which are likely to affect each of them in the future.
Forecasts include assumptions about increases in domestic demand due to greater use of appliances such as automatic washing machines and waste-disposal units, and decreases in domestic demand due to more showers and fewer baths, dual-flush toilets, and water metering to houses. They also include assumptions about population growth, the level of economic activity, climate change and the rate of leakage from the system.
More water is lost through leaks in the public water supply distribution system than is put to any one use. In 2002/3 the leakage in England and Wales was estimated as 3.6 × 106 m3 per day, around 22% of the water put into the system.
The leakage rate is greater in cities, where water mains date back to Victorian times, most of which are now dilapidated. Here leakage can reach 40%. However ‘lost’ is a relative term, as much of the water that leaks from the mains recharges aquifers.
Water is lost through continual gradual leakage, as well as from spectacular temporary bursts caused by vibration, soil compaction, corrosion or excavation when installing gas pipes and electricity and telephone cables. There are around 20 bursts per year in England and Wales for every 100 km of water mains - and there are over 3 × 105 km of mains.
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