Drinking water is not distributed evenly over the surface of the planet. Some areas have an abundance, others do not. Climate change means that some areas become more arid, causing widespread and long lasting droughts. Usage of various poisons in agriculture and other pollution is making it into ground water, slowly causing well after well to be unfit as a source for drinking water. On top of that, the consumption of water in many areas is larger than the replenishment due to rainfall, so local reserves are dwindling. In the richest parts of the world this is not much of a problem as alternatives exist, but they come at a cost.
Regarding fracking, the heavy use of water is an issue that has been raised, albeit I think mostly due to fear of the chemicals used seeping into ground water.