An argument for twin propositions is presented in this two-part paper: (i) that solving India's water problem requires a paradigm shift in agriculture (Part I), and (ii) that the crisis in Indian agriculture cannot be resolved without a paradigm shift in water management and governance (Part II). If farming takes up 90% of India's water and just three water-intensive crops continue to use 80% of agricultural water, the basic water needs of millions of people, for drinking water or protective irrigation, cannot be met. This first part argues that the paradigm shift in agriculture requires a shift in cropping patterns suited to each agroecological region, a movement from monoculture to polycultural crop biodiversity, a decisive move towards agroecological farming, and greater emphasis on soil rejuvenation.