Groundwater is the main source of irrigation in India, but there is a huge uncertainty about the number of groundwater structures. This paper compares data from four government sources on wells and tubewells, diesel pumps and electric pumps for time periods from the mid-1980s to the mid-2000s. There is a wide divergence in data, which is not attributable to mere time lags or definitional differences. This is a cause for concern, because lack of reliable estimates of these numbers affects realistic calculations of important variables such as groundwater extraction, electricity subsidies, and the carbon footprint of agricultural groundwater use.