When India overtook China as the world’s largest producer of rice this year, the country’s politicians and agriculture lobby marked the moment by praising resilient farmers and innovative government policy. India has nearly doubled the amount of rice it exported over the past decade, with shipments crossing 20 million metric tons in the latest fiscal year. But many rice farmers in the country’s agricultural heartlands are in a less celebratory mood. Interviews with growers, government officials and farm scientists, as well as a review of groundwater data, reveal widespread concern that thirsty rice crops are unsustainably draining India’s already-low aquifers, forcing farmers to borrow heavily to drill ever-deeper borewells. In the rice-basket states of Haryana and Punjab, groundwater was reachable at around 30 feet a decade ago, according to 50 farmers and eight water and agriculture officials. But drainage has accelerated in the past five years and borewells must now go between ...