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.