At a migration rate of three million people per week, three-quarters of the world’s people will live in cities by 2050. This will make the 21st century the first in which more people live in cities than, outside them. Certainly Alberta, for all its cowboy history, has become an urban society: about 3.5 million people, or about 82% of its residents live in cities. Adding to the threat of climate change — the 'threat multiplier' that affects air pollution, housing, and the economy, among other areas — this makes understanding anything that impacts urbanites, all the more urgent. Comparing water as the lifeblood of a city is not alarmist. As Cecilia Tortajada, of the University of Glasgow, observed, “[F]oreign investors tend to be most interested in megacities that not only have the most appropriate institutions, infrastructure and human resources, but also livable environments and natural resources that will sustain economic activities.” Water is first among them. Brice Lalonde, a former French environment minister, noted that 74 percent of the water consumed on the planet come from rain, making it an overlooked resource in large cities. In any scenario, finding ways of collecting more water is a good policy. But how?A case in point is our notoriously water-stressed neighbor, Mexico City. Rainwater harvesting in Mexico City takes advantage of its torrential, if unreliable rainfall and flooding — billions of gallons drinkable water per year. Collecting it also prevents the rain from doing hundreds of millions of dollars in damages annually.However, many large cities have not taken advantage of rainwater harvesting, even though their potential is “enormous.” In Hyderabad for example, (India,) it is estimated that 80,000 litres of water can be collected from 100 square meters of roof space, leading to 40 million cubic meters of rainwater collected each year. In total, 35 percent of domestic needs could be met in this way.In some smaller cities, such systems are already required in new homes, like Adelaide, Australia, and Santa Fe, New Mexico. In Brazil, over 650,000 units have been successfully set up. The percentage of the global population using them is predicted to rise from three percent to eight percent by 2030.Isla Urbana, a non-profit in Mexico City, installs rainwater harvesting systems in homes — at $750, a cheaper and more accessible variation on the traditional ones, which cost up to $10,000. They also last 30 years, compared to “dozens of years” for Brazil’s counterparts. While the initial water collected is not drinkable, it can be filtered to be potable. And, while some may argue that rainwater harvesting is not a long-term solution, it does help households and the government by providing a cheap source of water and unburdening the water trucks — the pipas — and other water distributors. Mexico City sources 40 percent of its water from elsewhere, and it will probably need to find even more water sources. Searching for new water sources is not new in the megacity. Since the pre-Hispanic era, the city has looked in the “springs of the surrounding mountains, then local groundwater, then surface and groundwater resources of other watersheds.” Lerma Valley is one such area, although it quickly succumbed to “groundwater overexploitation, subsidence, and flooding.” The government in Nuevo León is buying desalinated water from a nearby state, a strategy that may be replicable in Mexico City. Distribution of the water supply can be improved, as in Monterey, where $82 million has been spent to rent more pipas.Multiple sourcing therefore, has turned into a “crucial and long-standing strategy for households” in emerging megacities around the world. In Singapore and Israel for example, cities are encouraged to treat and reuse wastewater, as in a circular economy, to provide an additional source of water. (Membrane technology, used in desalination, has proven to be just as useful in purification.)In Alberta, the government has classified a series of responses to water shortages. Right now, the province is level four (out of five) with 21 advisories in May. Four major river basins have demonstrated “below average” water supply or worse. (In British Columbia, a similar warning is in place; the highest level anticipates “adverse impacts socio-economic and ecosystem values.”)In this era of climate change and extreme weather that seems to return annually, more needs to be done by non-profit groups and private sectors, incentivized by the government on all three levels. Perhaps it is time for Alberta to take an inspiration from places such as Mexico City — among many others — that have mobilized old technologies along with the new, to solve their water crisis.Gary Lai is a Canadian economist and award-winning author. His latest book is 'Poverty and the Unequal Society in Hong Kong' published by Penguin Random House.
