Indian Sundarban Biosphere Reserve (SBR) area lies in the south-western part of Ganges Brahmaputra delta and supports 4.43 million population. Though crisscrossed by numerous rivers and bestowed by good amount of rainfall annually, scarcity of potable water is a major problem in SBR. Most of the rivers in Sundarbans have been disconnected from their sources and don’t receive upstream flows. Shallow ground water in SBR is brackish to saline while fresh groundwater occurs below 300m depth. To achieve the sustainable development goal of providing water for all in the region, assessment of water demand, its availability and accessibility are essential. From the population and its projection, the potable water demand has been estimated as 9.21 mcm and 22.68mcm in the SBR for the years 1991 and 2051 respectively. The available potable water in Sundarbans is not adequate to meet the need of the future population. The people of SBR mostly depend on spot water sources which are not always easily accessible. To improve the availability and accessibility of potable water in the region, switching to treated surface water, rainwater harvesting, artificial recharge in the shallow aquifers, desalinization of shallow groundwater might be helpful.