limiting water waste

In addition to income levels, water prices help to set the extent of demand. For example, in the late 1990s, when my colleagues and I simulated global water use from 2000 until 2050, we found that worldwide water requirements would rise from 3,350 cubic kilometers (km3)—roughly equal to the volume of Lake Huron—to 4,900 km3 if income and prices remained as they were in 1998. (A cubic kilometer of water is equivalent to the volume of 400,000 Olympic swimming pools.) But the demand would grow almost threefold (to 9,250 km3) if the incomes of the poorest nations were to continue to climb to levels equivalent to those of middle-income countries today and if the governments of those nations were to pursue no special policies to restrict water use. This increased requirement would greatly intensify the pressure on water supplies, a result that agrees fairly well with forecasts made by the International Water Management Institute (IWMI) when it considered a “business-as-usual,” or “do-nothing-different,” scenario in the 2007 study Water for Food, Water for Life.

Ways to Limit Waste
Given the importance of economics and income in water matters, it is clear that reasonable pricing policies that promote greater conservation by domestic and industrial users are worth adopting. In the past the cost of freshwater in the U.S. and other economic powers has been too low to encourage users to save water: as often happens when people exploit a natural resource, few worry about waste if a commodity is so cheap that it seems almost free.

Setting higher prices for water where possible is therefore near the top of my prescription list. It makes a lot of sense in developed nations, particularly in large cities and industrial areas, and more and more in developing ones as well. Higher water prices can, for instance, spur the adoption of measures such as the systematic reuse of used water (so-called gray water) for nonpotable applications. It can also encourage water agencies to build recycling and reclamation systems.

Raising prices can in addition convince municipalities and others to reduce water losses by improving maintenance of water-delivery systems. One of the major consequences of pricing water too low is that insufficient funds are generated for future development and preventive upkeep. In 2002 the U.S. Government Accountability Office reported that many domestic water utilities defer infrastructure maintenance so that they can remain within their limited operating budgets. Rather than avoiding major failures by detecting leaks early on, they usually wait until water mains break before fixing them.

The cost of repairing and modernizing the water infrastructures of the U.S. and Canada to reduce losses and ensure continued operation will be high, however. The consulting firm Booz Allen Hamilton has projected that the two countries will need to spend $3.6 trillion combined on their water systems over the next 25 years.

When the goal is to save water, another key strategy should be to focus on the largest consumers. That approach places irrigated agriculture in the bull’s-eye: compared with any other single activity, conserving irrigation flows would conserve dramatically more freshwater. To meet world food requirements in 2050 without any technological improvements to irrigated agriculture methods, farmers will need a substantial rise in irrigation water supplies (an increase from the current 2,700 to 4,000 km3), according to the IWMI study.

On the other hand, even a modest 10 percent rise in irrigation efficiency would free up more water than is evaporated off by all other users. This goal could be achieved by stopping up leaks in the water-delivery infrastructure and by implementing low-loss storage of water as well as more efficient application of water to farm crops.
An agreement between municipal water suppliers in southern California and nearby irrigators in the Imperial Irrigation District illustrates one creative conservation effort. The municipal group is paying to line leaky irrigation canals with waterproof materials, and the water that is saved will go to municipal needs.