The Indian monsoon evokes images of torrential downpours and yearly flooding; indeed, some parts of the country receive more rain than any other region of the world. But most of this rainfall occurs during the summer months, and surface water sources are often ephemeral the rest of the year. No wonder then that many Indians turn to groundwater, be it for agriculture or for household use.

The fact that the nation's aquifers have been used and then overused over the past few decades was clear from the data compiled by Indian government agencies and non-governmental organizations. What was not available was a quantitative assessment of the regional groundwater budget. Two independent studies have now provided an estimate of net groundwater loss using a satellite-based technique (Nature doi:10.1038/nature08238; 2009 and Geophys. Res. Lett. doi:10.1029/2009GL039401; 2009). The results reveal that aquifers in northern India — the nation's most populous region with almost half a billion people — have been depleted at a mind-boggling rate.

Both studies used data obtained by NASA's Gravity Recovery and Climate Experiment (GRACE) satellites that were launched in 2002. The results provide indisputable evidence that the rate of groundwater withdrawal was greater than the rate of recharge during the six years from 2002 to 2008. As a result, the region's aquifers lost almost 300 km3 of water — twice the volume of water in the Dead Sea and about one tenth of the annual rainfall over the whole of India. It does not take much to imagine that the country's large and growing population will put further pressure on its finite natural resources. But these figures are higher than official estimates and should serve as a definite wake-up call.

The Indian government does not have a strong track record in pre-empting looming disasters. The Indian public would therefore be forgiven for wondering whether the prospect of rapidly dwindling groundwater resources will serve as an impetus for prompt action. There is no paucity of sound advice regarding what needs to be done, however, and the government would do well to heed that.

Scientists and non-governmental organizations have long been advocating an intelligent, effective and equitable policy to manage water resources (for example, http://tinyurl.com/pu5adg). There is no question that available water should be used more efficiently with minimum wastage. Recharging aquifers by reducing runoff and facilitating percolation needs to be taken up with renewed vigour. Changes in the groundwater budget ought to be monitored at all levels, local as well as regional, and this information should be made accessible to consumers as well as policymakers.

India is the largest democracy in the world, something that its leaders and elite never tire of repeating. But regardless of the nation's adroitness in conducting general elections on a mammoth scale, it remains a sad fact that those who are likely to be most affected by a given issue often have the least say in it. Decreasing stocks of groundwater in northern Indian will undoubtedly have a disproportionate impact on the region's rural population and the urban poor.

India has thousands of voluntary organizations and millions of concerned citizens whose dedication and motivation are exemplary. Whether the various levels of government in India buck the trend and engage these stakeholders in a serious discussion remains to be seen.