But then the great urbanization of India began in the 1970s. Unlike Delhi and other cities, which went vertical, Chennai spread horizontally. Wetlands and swamps were covered over. The arrival of air-conditioning meant that when they built things now, developers and city officials didn’t bother to think about sea breezes or airflow. Traditional wells were replaced with deep-bore wells, which were dependent on the region’s deep aquifer, which, among other things, was prone to saltwater intrusions that made it undrinkable.
