Mega-Cities Squander Water Resources

If Latin America's major cities, like Sao Paulo and Mexico City, don't enact policies for conservation and efficient use of water, they will soon have to ration this vital liquid, warn experts.

RIO DE JANEIRO - Brazil and Mexico's mega-cities are devouring as well as contaminating their water resources, and forced to seek increasingly distant supplies. But experts stress that the problem is not scarcity but rather widespread waste.

"It is essential to reduce excessive consumption," Brazilian expert Aldo Rebouças told Tierramérica. He said "management of demand" is the only way out of the water supply crisis in the Sao Paulo metropolitan region, which could face rationing in the coming months.

The threat has been looming since last year over the 18 million residents of the greater Sao Paulo area, which comprises 38 municipalities. Torrential rains during the southern hemisphere summer caused many floods, but did not reduce the water supply problem.

The rains were more intense in flood-vulnerable low-income districts than in the areas that most needed it and which feed the reservoirs, in the Cantareira sierra.

The Cantareira system of dams, which supplies half the metropolitan region, is at just 17 percent its total capacity and would have to reach 40 percent by the end of the month to stave off rationing, say the technicians at the Sao Paulo state sanitation company, SABESP.

They decided -- "a last-ditch attempt to prevent collapse" -- to offer customers who reduce consumption by at least 20 percent a proportional discount in their water bills over the next six months.

SABESP has a production capacity of 68 cubic meters of water per second (m3/s) for the metropolitan region, but cut back to 61 or 62 m3/s in the last few months, Francisco José Paracampos, planning and distribution superintendent, told Tierramérica.

Because of the scant margin, vulnerable to the smallest drought, the public enterprise, which holds a monopoly in Sao Paulo over water distribution is drawing up plans to boost production by 12 to 15 m3/s over the next 15 years, said Paracampos.

That approach maintains a "culture of abundance", increasing supplies instead of promoting conservation and efficient use of water resources, says Rebouças, hydrology engineer at the University of Sao Paulo. Per capita water consumption today in greater Sao Paulo is 180 liters per day, but 100 liters would be sufficient, he adds.

The new projects are very costly because they rely on water supplies that are farther away from the city, with additional energy expenses for elevating the water to the Sao Paulo altitude of 800 meters above sea level, explained the expert.

But Paracampos disagrees: SABESP plans combine increased supplies with regulation of demand. Per capita water consumption in Sao Paulo "decreased 20 percent in the past six years," he said.

Problems similar to Sao Paulo's are found in the Valley of Mexico metropolitan area, comprising the Mexican capital and the neighboring state of Mexico, home to 20 million people at an altitude of around 2,240 meters.

The region is favored by abundant underground water resources, which cover 70 percent of the demand, but overexploitation has caused the land to sink as well as damage to buildings and infrastructure.

Extraction of water exceeds the natural recharging capacity of the aquifers by an estimated 50 to 80 percent, and official plans call for drawing even more water from them and from rivers that are farther away and at lower altitudes.

Furthermore, experts calculate that 35 percent of water supplies are lost in leaks throughout the distribution system.

If corrective measures are not taken, says the GEO (Global Environment Outlook) study by the United Nations Environment Program, the water deficit in the greater Mexico City area will be 21 cubic meters per second, the equivalent of 46 percent of consumption today.

Major investments are being made in the area's deep drainage system, which already has 153 km of tunnels, and is to add 39 km more by 2007 at a cost of 760 million dollars. The aim is to prevent flooding, an ongoing problem for a city that was built over what used to be a series of lakes.

Mexico City also suffers from serious institutional confusion, with more than 20 administrative bodies overseeing water resources. "There is a duplication of effort in management, contradictory policies between agencies in the same city," noted Manuel Perló, director of the University Program for City Studies.

In Mexico City and Sao Paulo alike, the authorities are carrying out campaigns to promote water conservation and reduced consumption. But in Mexico, subsidized rates for water utilities undermine that effort.

Crisis repeats itself in Sao Paulo with no effective change in strategy, according to Rebouças. The new projects entail pipes to distribute 250 liters of water per person per day, which, he says, is a waste-level volume.

Increasing the supply also implies additional costs in drainage, given that 80 percent of potable water ends up as sewage, Ivanildo Hespanhol, a University of Sao Paulo expert in water reutilization, told Tierramérica.

In addition to raising public awareness, water fixtures needs to be replaced. "In toilets, which represent 26 percent of residential consumption, the discharge could be reduced to six liters of water, one-third of the current volume, without losing efficiency," said Hespanhol.

Re-use of water could delay the need to tap new and distant sources, he said. It can be used in agriculture, in industries that are major water consumers, in street cleaning and in irrigating urban green areas.

Dozens of industrial companies are already using "used water" in greater Sao Paulo. But this new alternative "has to be imposed as policy," because the sanitation companies are not interested -- their bottom line would suffer due to the lower costs of reusable water, Hespanhol said.

* Mario Osava is an IPS correspondent. Diego Cevallos contributed reporting from Mexico.

• Tierramérica special edition: Water