A troubling new study released this month by an Indian government think tank finds that 21 cities, including New Delhi, will run out of groundwater by 2020, and by 2030, about 40 percent of the population will have no access to clean drinking water. Roughly 600 million Indians are facing high to extreme stress over water, the report said, and at least 200,000 people die every year because they do not have access to uncontaminated water.