TECHNICALLY, Mexico has enough water to meet its needs. But the water's uneven geographic distribution causes problems with water supplies and sewage systems.
While more than 85 percent of the country's water is located in areas under 500 meters in altitude, 70 percent of the population and 80 percent of industry are located above that altitude. Consequently the northern part of the country has a 12.3-billion- cubic-meter (16-billion-cubic-yard) deficit, while the southeast has a 200- billion-cubic-meter (260-billion-cu-bic-yard) surplus.
This imbalance is reflected in water availability throughout the nation. The southeast endures serious damage during heavy rainstorms, while the north copes with a lack of water and the center has supply difficulties related to its huge urban concentration and industrial zones.
As a result, 25 million people do not have potable water and 44 million are not hooked up to the sewer. Proportionally this means that only two-thirds of the population has direct access to the precious resource of clean water and only half has access to the indispensable service of collecting and purifying waste water.
But behind these statistics is the fact that while almost all cities are equipped with suitable installations, most sparsely populated areas are not. The metropolitan zone of Mexico City supplies 93 percent of the potable water demand, while in the rest of the country, barely 65 percent of the need is covered.
The sewer systems mirror this problem, but are in worse condition. According to National Water Commission (CNA) estimates, only 70 percent of the need in Mexico City is met. Seventeen of the municipalities do not even have sewage systems.
CNA also estimates that only 50 percent of the need in the rest of the country is met. Other researchers believe that figure to be closer to 30 percent.
From as early as the 17th century, when the viceroy, the Marquis de Cadereyta, ordered the construction of a drainage ditch to carry away the waste water from the valley basin, there has been inequity and antagonism between the city and the countryside. Several statistics and critical events allow measurement of the distance traveled thus far.
Overall, CNA estimates that urban areas have some 12 million people without potable water and more than 21 million without sewers. In rural areas the figures are slightly higher - 13 million lack clean water and 23 million people do not have sewers. In addition, each year the nation's population growth demands that an additional 3 million people be supplied with drinking water.
According to Gloria Gonzales Salazar of the Economic Studies Institute of the National University, 70 percent of Mexico's water needs are filled by 1,365 wells and 60 other sources located south and west of the capital, Mexico City. The rest comes from the Lerma and Cutzamala rivers.
In order to transport water into the city, 443 kilometers of pipes feed 202 reservoirs. The total capacity of these reservoirs is 1.5 million cubic meters. To ensure delivery of water to elevated areas south and west of the federal district, the system also includes 102 pumping stations and a pipe network of more than 1,200 kilometers.
This system means that about 97 percent of the district is supplied with potable water. The region consumes 35.5 cubic meters (46 cubic yards) of water per second - the largest portion used for domestic purposes, followed by industry, public services, and businesses.
Mexico City has a just-completed 13,000-kilometer (8,000-mile) water-purification network with 64 pumping stations and a 90-kilometer (56-mile) drainage system located by the Nochistongo Canal. Waste water is thus drained away towards Hidalgo. The water is treated at nine purification stations that have a combined capacity of 5 cubic meters per second. These facilities, however, are used only to about 30 percent of capacity because of inadequate storage facilities.
As for agriculture, Mexico ranks sixth in the world in terms of available irrigable land. Seventy-seven government districts hold 60 percent of irrigable land, and private property accounts for the rest. But the 50 billion cubic meters of water used annually for irrigation are only one-third of total national consumption. And the users cover only 30 percent of the maintenance and operational costs.
A stated government goal is to increase the supply of water to allow for irrigation of an additional 800,000 hectares (2 million acres). To provide for this, the government will increase the budget for irrigation engineering work by 55 percent and will put in place mechanisms to increase collection of water-use fees.