Development & Aid, Environment, Tierramerica

The Goal: Not a Drop Wasted

SAN FELIPE DEL PROGRESO, Mexico, Sep 14 2009 (IPS) - A variety of new methods for making best use of rainwater are being tested in Mexico, which faces water shortages that will only grow worse in the coming decades.

Geomembranes to collect and filter rainwater. - Emilio Godoy/IPS

Geomembranes to collect and filter rainwater. - Emilio Godoy/IPS

In his novel “México sediento” (Mexico in a Drought), author Francisco Moreno postulated that drought would lead to war in 2010, a repeat of water shortages detonating the fight for Mexico's independence from Spain in 1810 and the Mexican Revolution in 1910.

Although the lack of water is a historic trait, Mexico today is suffering a severe crisis as a result of the depletion of underground springs and scant rainfall.

In Mexico City, one of the hardest hit areas, one option is to make use of what rain does come, which otherwise goes to waste. Some 17 cubic meters of rainfall go down the drain every second.

A good example of utilizing rain is under way in the municipality of San Felipe del Progreso, some 150 kilometers from the capital, where a rainwater collection and purification plant is operating.

With technology developed by the International Center for Demonstration and Training in Rainwater Usage (CIDECALLI), of the Postgraduate College, and with funding from private donations, the non-governmental Pro Zona Mazahua Sponsorship invested 1.5 million dollars in the project launched in 2006 to supply marginalized areas and to prevent gastrointestinal diseases.

“It has been difficult to introduce the water that we purify, because people have gotten used to drinking soft drinks,” Manuel Figueroa, head of the plant, told this reporter.

The site has a slope with a geomembrane that channels rain to two enormous basins with more geomembranes, low-permeability sheets made from plastic resins. They filter out particulate from the water, which passes to a tank, from which it flows into purification machines and into 19-liter bottles. This final phase takes five hours.

The installed capacity is five million liters, and 4,000 liters are processed daily, of which 2,500 are utilized and the rest goes to irrigating the plant nursery of forest species being grown as part of the project.

The project's brand, “Más-Agua”, is distributed to the rural homes and schools in the area, populated by Mazahua Indians. The prices vary between 75 cents on the dollar and 1.10 dollars per bottle.

“We began to look skyward and we asked ourselves why weren't we taking advantage of rainfall, which is a valuable resource and easy to treat and make potable. Our project is 30 years old and they asked me when it would be viable. I responded that it would happen when we reached a crisis. That moment has come,” Manuel Anaya, CIDECALLI coordinator, said in an interview for this report.

A group of professors from the College of Postgraduates, specialized in agricultural sciences, and the autonomous universities of Chapingo and Antonio Narro, created CIDECALLI in 2004.

The Mexican capital, with some 12 million inhabitants, consumes 33 cubic meters of water per second. Due to leaks in the pipes, every year around 150 million cubic meters are lost. From the city's aquifers, water is consumed at a pace of 55.5 cubic meters per second.

Given the lack of rain in the last three months, the government's National Commission on Water, and the capital's water system have reduced the supply. Officials warn that if the crisis continues, the capital will have no water in February 2010.

The rainwater collection systems are “replicable, economical, accessible and give good results,” said Enrique Lomnitz, director of the non-governmental International Renewable Resources Institute-Mexico.

Within the “Urban Island” project, Lomnitz and his team have set up five collection systems in homes in a low-income district in southern Mexico City. The parties involved provide the materials and the project sets it up, free of cost.

The system involves a pre-filtration mechanism, a cistern with chlorine to disinfect the water, and a filter, for a total cost of 115 to 190 dollars. Each meter of rooftop can supply one liter of water.

“We are concentrating our efforts on a specific site in order to create a prototype on a neighborhood scale, one that can be monitored and easily managed,” explained Lomnitz, an industrial designer with a degree from the Rhode Island School of Design in the United States.

Faced with a worsening crisis, the non-governmental Center for Research on Development (CIDAC) designed a pilot project for rainwater collection at 120,000 houses, equivalent to 10 percent of the city's residences.

CIDAC proposes that the governments of the capital and of the neighboring state, also named Mexico, finance the initiative, whose cost per house is 350 dollars, and which would lead to savings of approximately 7.2 million cubic meters of water annually.

The use of rainwater collected by households in tanks has proved successful in other arid regions of the world, such as the Brazilian Northeast.

The promoters of “Más-Agua” purchased a bottling machine that handles 48 half-liter containers per minute. But San Felipe del Progreso, a city of some 100,000 people, faces a common national problem: lack of rain. And if water doesn't fall from the sky, the factory won't have anything to purify. The alternative will be, then, to process water from the area's springs and wells.

But, if done right, the water collected during rainfall is enough to cover the dry months – from November to May.

 
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