Half of the world's people now live in cities, according to the United Nations, and within two decades, nearly 60 percent of the population -- 5 billion people -- will be urban dwellers.
Developing countries feel the growth most directly, but even cities like Philadelphia are showing signs of population growth.
While cities are considered by many to be the most environmentally benign habitat for human beings, urban population growth brings challenges. Among those challenges are increasing stresses on water availability, access, and sanitation.
Cities are hard to sustain without reliable access to safe drinking water and adequate sanitation. Yet even in the industrial world, urban water and waste service infrastructure is not up to the challenge.
Scarcity of usable water around the world is leading to further challenges and economic constraints, according to William Brennan of Summit Global Management,
a San Diego-based investment firm that specializes in water.
"The continued industrialization of emerging markets, growing global agricultural demand, and rising energy inputs are unstoppable trends that are all converging at a historic rate, making the water demand curve further accelerate," Brennan wrote to me recently.
Yet, with such challenges also come opportunities, especially where recycling and reuse and treatment of water and wastes are concerned.
In the US, start-up companies like Liberty Hydrologic Systems, BlackGold Biofuels, Cardinal Resources,
and ET Water
are coming up with innovative solutions to deal with treatment, filtration, and waste; while large utilities such as AquaAmerica
and American Water
tackle the infrastructure for drinking water and wastewater services.
Internationally, organizations such as charity:water
and the Global Water Challenge
are addressing clean, safe drinking water, and sanitation issues in developing nations. (Here is a comprehensive list of water related organizations: H20.
"Good urban water management is complex and requires not only water and wastewater infrastructure, but also pollution control and flood prevention," as the organizers of World Water Day
point out. "It requires coordination across many sectors and between different local authorities and changes in governance that lead to more sustainable and equitable use of the urban water resources."
It also requires innovative solutions and new ways of thinking about how we use, reuse, conserve, and treat our water.
One day each year hardly seems adequate to raising the awareness of water issues around the world, but it's a start. As our cities expand and stresses to water supplies increase, it will become clear as...well...water that we need to pay more attention to this most precious resource.
Join me and Dr. Paul Bowen of Coca-Cola, Larry Levine of NRDC, and Richard Murphy of Fortune for a webinar today at 1PM ET as we discuss water challenges and opportunities: Cities and the Global Water Crisis.