The demand side of the issue

Water-supply problems are not alone, however. In fact, the water problem has two sides: the availability of resources - or the supply side - and water-consumption issues - or the demand side. Many water-supply problems would not exist, or would be much less acute, if more sustainable policies and strategies were formulated and implemented that better accounted for the demand side.

In most countries and cities, consumption is actually much greater than what is required to serve human activities. Wastage takes place at all stages in water systems: leakage from pipelines, wasteful attitudes encouraged by a lack of metering or inadequate pricing policies, inappropriate water-appliance technology, etc. To improve the situation, this waste must be reduced through improved management strategies.

In most urban areas, water shortages could be prevented for many years with better system maintenance and appropriate metering and pricing policies. Such a strategy would be more economical in terms of both time and money and would reduce the deleterious effects on natural water systems. However, very few cities in the world have moved toward such a sustainable approach to water management. This lack of action is related to the types of development models that have been adopted in most countries.

Sustainability and equity in urban areas

To solve urban water-supply problems, management strategies must weigh required investments against returns within a framework of sustainability and equity. For every densely populated area of the world, there are several possible sustainable and equitable water-supply options. Usually, once sustainability and equity are assured, the main criteria for choosing among the various alternatives would be the financial costs of the proposed systems.

Many other factors enter the equation, however. Some relate to the concept of sustainability. First, water-supply systems should not affect the sustainability of the water resources themselves (that is, the rate of use should not be higher than the rate of renewal, and the quality should not be lowered). Second, the sustainability concept includes protecting other natural resources in the region (fluvial or lacustrine ecosystems should be protected).

In addition to ecological sustainability, water systems must be socially sustainable. The implementation of any water system involves socioeconomic implications, not only from the perspective of satisfying the needs of all the population in an equitable way, but also from other points of view. Establishing water services creates employment, promotes some types of industries, and even affects other urban strategies (for example, the availability of water will stimulate the development of some neighbourhoods over others).

Water and models for development in urban areas

Even with sustainable approaches to water management, population growth in many areas exceeds the potential of local, natural systems. In those cases, the problem does not lie in the resources, but in the development models that have flourished throughout the world during the last few decades and, in fact, the last few centuries. It is clear that megacities are not sustainable entities. One wonders, for example, about the future of Mexico City, with 20 million people and still growing. Water is becoming insufficient and huge amounts of money and energy are being spent to produce larger and larger volumes of water, but the city and surrounding urban centres (Toluca, Puebla, Cuernavaca, and Cuautla) are still growing. The development model of Mexico City must be reviewed, growth should be curtailed, and the country’s economy and management system must be decentralized. If these things are done in an intelligent manner, there is a real possibility that the water problem will disappear, or at least be significantly reduced.

In the Philippines and Thailand, the increasing centralization of the economies in two megacities is not sustainable. Neither Manila nor Bangkok is located in an area that can accommodate an urban population exceeding 10 million without irreversible deterioration of the environment, including the water supplies. The problem is also apparent in Brazil. Hydrologically, Sao Paulo was in the wrong place to start with, and time and further growth of the city have worsened the situation. A new model requiring the relocation of some of the city’s activities may be the only long-term solution to many of its serious problems, including its water supply. The same arguments could be applied to many other cities of the world; Tehran, Bombay, Dakar, Kinshasa, Lagos, and Lima, to various degrees, present similar problems.

Irrigated agriculture: one of the largest water users

In most countries, it is not urban populations that require the largest volumes of water, but irrigation. Irrigated farming uses an enormous amount of water, especially because areas that require watering to grow crops are normally located where evaporation rates are high, and this is exacerbated by the type of crops planted, some of which have high transpiration rates.

On 1 hectare of irrigated rice, for example, as much as 20 thousand cubic metres of water may evaporate every year. Even for less-demanding crops, irrigated farms use as much water for each hectare, on average, as 40 urban homes. For this reason, irrigated agriculture can be competitive only if crops of high market value are grown or where the price of water is very low.

Frequently, the low price of water for irrigation does not reflect actual costs. In some irrigated zones, water is obtained from systems in which the cost of expensive dams or other waterworks has not been factored into its price. The artificially low cost of water allows the development or persistence of irrigated farming in areas where it would otherwise be economically unfeasible. In those cases, farming only survives because it is being subsidized by the institution or agency that built or financed the waterworks and is not passing along the cost to the water users.

In many cases, the capital investment was financed by a loan to a national government and is being repaid by society at large. In California, for example, large hydroworks on the Colorado River and elsewhere were financed by the federal government. In Mexico, as well, the investment needs of most irrigation districts, as well as a considerable part of the pumping costs, are or were supported by the federal government.

Defining water strategies

One of the pressing problems facing those developing strategies for the future relates to the allocation of water to the often competing areas of irrigated farming and urban use. Farmers use far more water than urban dwellers (even when large water-consuming industries are considered).

For this reason, the competitiveness of agricultural activities is closely related to the cost of water. Expensive water can exclude the farmer from the market. Urban dwellers can afford to pay more per unit of water because the cost of aquiring the water is shared by many more individuals and enterprises and because they use much less water on a per-capita basis.

In the competition between farmers and cities, the cities tend to have the upper hand. In some cases, this may be to the detriment of traditional farming activities by many small farmers who depend on irrigation (such as in Egypt). In other cases, speculative water policies result in water being taken from small farmers or indigenous communities and provided to large companies for commercial production (for example, the water transfer from Owens Valley to the lower valleys in California).

For this reason, it is necessary when defining water strategies to take into account all the elements of the equation.

· How much water is available?

· Who needs it the most?

· What share should be provided to each user?

· Who has priority?

· What makes the most sense economically?

Finally, these concerns must be answered within the framework of sound development models in which quality of life and sustainable use of resources are the main priorities. Use of water resources will be optimal and the water situation will be addressed satisfactorily only when sustainable social and environmental models are properly defined and adopted.