How to Conserve Water Efficiently-BECKER
The sharp rise in world population and income during the past five decades has stimulated greatly increased demand for clean water, and concern about whether the supply of water would be adequate to meet these needs. Demand for usable water in the future will surely continue to grow at a significant pace unless steps are taken to reduce demand, while the supply of water could grow more slowly, especially if global warming reduced rainfall and increased evaporation of water. The best way to bring demand into balance with supply is to introduce much more sensible pricing of water consumption than is common in most countries.
Many discussions of water conservation create the impression that households are large and inefficient users of clean water for drinking, eating, bathing, and toilet flushing. That is a myth. About 40 per cent of all the freshwater use in the United States is for irrigating land for agriculture, another 40 percent is used to produce power, and only 8 percent is used for domestic use; these percentages are similar in other countries. Moreover, about a third of all the water used by households in rich countries goes to water lawns and for other out door purposes, so probably no more than about 5 per cent of the total demand for water is for personal use.
Water used is usually a poor measure of the net amount of water consumed since much water is returned either immediately, or after evaporation and condensation, to the source pool, where it can be used again. Thermoelectric plants use a lot of water for cooling purposes, but typically have a very high reutilization rate (about 98 percent). Household use is also efficient, with a reutilization rate of about 75 percent. As a result, neither power producers nor households are big net consumers of water. Irrigation of farmland absorbs much water since most irrigation systems have low reutilization rates. In California, the biggest water using state, irrigation systems have a reutilization rate of only about 40 percent...
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