The theme of 2011′s World Water Day is Water for cities: responding to the urban challenge. By virtue of sheer numbers, India more than any other country in the world needs to wake up to the formidable challenge it faces in the years ahead.

According to the UN: This is the first time in human history that most of the world’s population live in cities: 3.3 billion people …and the urban landscape continues to grow. 38% of the growth is represented by expanding slums, while the city populations are increasing faster than city infrastructure can adapt.

Here’s another statistic that is simply staggering: Urban expansion in India will happen at a speed quite unlike anything the country or the world has seen before. It took nearly 40 years (from 1971 to 2008) for India’s urban population to rise by nearly 230 million; it will take only half that time to add the next 250 million. (Read full report at McKinsey Quarterly)

India’s cities burst at the seams decades ago. Water and sanitation are no longer just ‘poor people’s problems.’ Hari Bhatti’s photo essay on Delhi’s nallahs is a wakeup call to anyone who thinks it is.

Via Hari Batti's Green Light Dhaba: A Delhi drain choked with garbage that ultimately ends up in the Yamuna river.