What can be done to use water more efficiently and reduce withdrawal and consumption? Since irrigation is one of the largest consumptive uses, improved agricultural irrigation could reduce water withdrawals by between 20 percent and 30 percent. Poor irrigation practices waste a tremendous amount of water. In some cases only a small percentage of the irrigation water used actually goes to the target plant. Techniques to improve water conservation for agriculatural irrigation include using lined and covered canals that reduce seepage and evaporation; computer monitoring and scheduling of water releases from canals; a more integrated use of surface waters and groundwaters; night irrigation, which reduces the amount of evaporation; improved irrigation systems such as sprinklers and drip irrigation; and better land preparation for water application.
Domestic use of water (urban and rural) accounts for only 10 percent of the total national withdrawals. However, domestic use is concentrated, and it poses major local problems. Withdrawal of water for domestic use may be substantially reduced at a relatively small cost with more efficient bathroom and sink fixtures, watering lawns and gardens at night, and drip irrigation systems for domestik plants.
Water removal for thermoelectricity could be reduced as much as 25 percent to 30 percent by using cooling towers designed to use less or no water. Manufacturing and industry could curb water withdrawals by increasing in-plant treatment and recycling of water or by developing new equipment and processes that require less water. The field of water conservation is changing so rapidly, it is expected that a number of innovations will reduce the total withdrawals of water despite increased consumption.