Mexico City

By Miguel Sanchez Enkerlin

As the 20th century progressed, the capital of the United States of Mexico, Mexico City, grew rapidly. Possibly due to government corruption, and neglect for the people, the city becameuncontrollably large and famous for its air pollution problems. Naturally, other problems arose; skyrocketing crime, rampant poverty, and a constant struggle to provide the enormous and mostly impoverished population with appropriate infrastructure.

By the 1990’s, about half the population (40 million) of Mexico fell below the poverty line, and about 15 million citizens in extreme poverty. The extreme poverty was concentrated around the urban centers, logically, the majority, around Mexico City, by far the countries largest city. By then, the population had reached over 18 million, and by the 2000s, the dire situation for the poor (a majority) had only worsened. The City itself is continuously causing problems for itself. Aside from its shocking pollution levels and traffic, the city takes in too much water; subsequently it has raped its own (previously rich) supply of subterranean water, and began to take water from neighboring states. Part of the problem is that the city consumes about 1.5 times the water per person per day that other cities in Mexico take in (300L to 200L), a problem which is due to how cheap the local government makes the water, yet it’s not drinkable, making Mexico the second largest consumer of bottled water, producing even more pollution. The water that is being taken has had far-reaching side effects on the nation as a whole. The city’s thirst has triggered droughts in Mexico’s countryside, causing cattle deaths (over 100,000), and crop losses, which are only expected to worsen with an estimated 20 million tones of crops at risk. Some believe the now scarce subterranean water supply of the city can be replenished slowly, by revitalizing the forests at the foot of the great mountain, or rather volcano, the Popocatepetl. Federally paid biologists now take care of the nation park between the volcano and the city that is rich in pine trees. They are hoping to restore the “water factory”, a naturally occurring retention of water by the ecosystem, which replenishes its water supply. The pine trees collect/retain rainwater, which then goes to the underground wells. Currently there are not enough trees and cattle in the park are consuming part of the water. The program works at maintaining and replanting trees, and taking are of the excess cattle in that area. If successful, this government program could gradually restore the city’s natural supply.

Sources;

Reuters Video - http://www.youtube.com/watch?v=QFPQu9zgl8E
Al Jazeera- http://www.youtube.com/watch?v=mrstdjPYf6Q

Roof Catchment Rainwater Harvesting Systems

The Region of Waterloo has taken to organizing Rain Barrel Distribution Events every April. Over the course of eight years, they've sold 34,000 rain barrels to interested citizens at a cost of $30 each. Overall, it appears to be a fairly productive project for the municipality to undertake.

Source: Region of Waterloo (link above)

Most rainwater harvesting in Canada appears to make similar use of the roof catchment systems used by the rain barrels being sold here in the region. The barrels are used for the collection and storage of rainwater from the roof, mainly for gardening. However, there is so much potential within the realm of this basic technology that should be explored beyond simple suburban lawn maintenance. The good news is it is being explored on a larger scale, with many different end purposes in mind.

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In case you were unaware, the vast majority of our buildings are designed with roofs. In climates where it can be a problem, polling of precipitation is avoided by sloping roofs; furthermore, most buildings feature gutters that exist for the purpose of moving water from the rooftop to a preferable location away from the building.

Incidentally, the roof catchment rain harvesting system is nearly identical to these systems as they already exist: the addition of a tank for storage of the rainwater makes the most basic household water harvesting system possible. Additions to this design are predicated on the intended purpose of the system- for example, outdoor rain barrels can feature a filter to prevent leaves and debris from entering the barrel, which could lead to increased maintenance requirements. It also prevents mosquitoes from using the standing water as a breeding ground, which eliminates the possibility of disease being spread.

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In terms of larger scale rainwater harvesting systems, we have several options for exploration. Based in British Columbia, The Rainwater Connection is a company that specializes in the development of personalized rainwater collection systems for homes that only have access to wells with high contaminant levels.

An example of the systems they create is the house on Galiano Island, which is fitted with leaf traps, ultraviolet filters, and a 15,000 gallon storage cistern.

Source: Rainwater Connection (Link Above)

This allows the household to use solely rainwater for all tasks, including toilet flushing, which accounts for 30% of the water used in Canadian households. Having a wet waste disposal system is extremely beneficial, for obvious reasons.

This system is expensive, as you would expect. However, cheaper alternatives exist- the Global Water Challenge has installed several roof collection systems on schools in Tanzania for hand washing at far cheaper cost. While the filtration systems used are not as intricate as those of The Rainwater Connection, the fact is that with little investment, these systems work.

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Rainwater and Subsistence

Source: www.re-nest.com (link below)

This second story rooftop garden is watered by sub-irrigation with a rain barrel watering system. The rainwater falling on the roof is diverted into a series of several rain barrels in the basement of the building where it is stored until the water is required, at which point a pump is activated to bring the water onto the roof. This is a relatively small-scale system costing around $700, which is admittedly not incredibly cheap, but the value of the system is the opportunities it holds for urban agriculture- being able to grow the food you eat within the city, defying any reliance upon external farms and shipping fees, is vital to the concept of subsistence.

Furthermore, consider lavatories running entirely on rainwater collected on roof and fed downwards. The Rainwater Connection has altered at least one set of public washrooms to completely make use of rain harvesters. A larger system isn't inconceivable, as long as the waste has a destination.

There would be technical issues- preventing debris and leaves from entering the is a main issue that must be avoided, and filtration and purification systems may also be a requirement, but these issues are not particularly difficult to address.

Feasibility should also be touched upon: Peru wouldn't benefit, but there are areas that could: Kowloon Walled City, as an old example, in a region that receives 2500-2800 mm of rain per year.

Source: HKO

The city was approximately 6.5 acres in size, so assuming a reasonable amount of rain- 2600 mm- approximately 68 million liters of water falls on this patch of land every year (The average Chinese individual uses 86 liters of water daily, though subsistence conditions would anticipate less.) Not all locations receive as much rain as Hong Kong, obviously, but even in locations that receive 200 to 300 mm of rain a year could make use of rainwater harvesting to supplement further water sources.

The simple fact is that the systems are simple, easy enough to construct, and extremely beneficial for obtaining water for many purposes without having to rely on traditional infrastructure for access. In a subsistence urbanity, this is, quite simply, a extremely vital building block.

-Sean Maciel

Bibliography



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"Global Water Challenge." Global Water Challenge. http://www.globalwaterchallenge.org/programs/projects-detail.php?id=818 (accessed November 4, 2009).


 

"How To: Rain Barrel Watering System." Re-nest: abundant design for green homes. http://www.re-nest.com/re-nest/february-jumpstart-2009-entries/how-to-rain-barrel-watering-system-breannes-february-jumpstart-project-2009-077398?image_id=4151 (accessed November 4, 2009).


 

"Kowloon Walled City." Welcome to the World of Archidose!. http://www.archidose.org/KWC/Main.html (accessed November 4, 2009).


 

"Living in the Region of Waterloo." Regional Municipality of Waterloo. http://region.waterloo.on.ca/web/Region.nsf/8ef02c0fded0c82a85256e590071a3ce/ef0dac1e32543d6185256b05005a2bfa!OpenDocument (accessed November 4, 2009).


 

"The Rainwater Connection Home Page." The Rainwater Connection Home Page. http://www.rainwaterconnection.com/ (accessed November 4, 2009).



"Water-Wise Tips for Bathrooms." Environment Canada. http://www.ec.gc.ca/water/en/info/pubs/brochure/e_IWDWW3.htm (accessed November 4, 2009).