If there is any single most important issue that mars bilateral relations among the countries of the subcontinent, it is water. The issues of cross-border water distribution, utilisation, management and mega irrigation/hydro-electric power projects affecting the upper and lower riparian countries are gradually taking centre-stage in defining interstate relations as water scarcity increases and both drought and floods make life too often miserable. Thanks to its location, size and contiguous borders with other South Asian countries, it is India, in its capacity as both upper and lower riparian, that has come into conflict with most of its neighbours, except Bhutan, on the cross-border water issues. Given an atmosphere of mistrust, an upper riparian India has serious issues to resolve with lower riparian Pakistan and Bangladesh and, despite being lower riparian, with the upper riparian Nepal. This, however, does not mean that India is solely responsible for certain deadlocks, even though its share of responsibility may be larger than other countries which have their own physical limitations and political apprehensions. As elsewhere in the world, and more particularly in the subcontinent where population explosion continues and environmental degradation worsens, water resources, like energy, are going to be much lower than the increasing demand, even if they are harnessed to the most optimum. Given the depleting resources of water, the issues of human security, and water security as its most crucial part, are going to assume astronomical proportions.