Over the past few decades Agricultural irrigation in South Asia has emerged to be dominantly groundwater sourced. The size and structure of a region’s groundwater economy is closely intertwined with its energy economy. Until only a few years ago, diesel was the main source of energy for groundwater irrigation in the region while farmers in the rest of South Asia had access to subsidized or free electricity to operate their pumps. With rapid improvements in rural energy supply, this energy-divide is now disappearing. This has potential to change the area’s groundwater energy nexus. Farmers in Bihar, a populous state of India, have installed more than 200 thousand electric pumps for irrigation since 2015. We use data from a representative sample of 1440 farmers from the state to assess the pattern of electrification of groundwater irrigation and its impact on pump ownership, water markets, and water use in agriculture. Electrification of irrigation is skewed towards west and south Bihar. On average, electric pump owners have smaller landholdings than diesel pump owners and they charge significantly lower irrigation fees from water buyers. However, three out of four pump owners report not selling water from their pumps. Farmers using electric pumps—owned or rented—irrigate their crops more intensively and have higher cropping intensity. Near free electricity for irrigation may undermine the fiscal and environmental sustainability of the irrigation led agricultural growth in Bihar.