Yeah, we need water; some cities with potential shortage

http://www.weather.com/news/science/environment/water-shortages-top-20-cities-risk-water-supply-drought-20130806

"A 2012 study conducted at the University of Florida rated water availability and vulnerability for 225 urban areas nationwide, based on available fresh water per person. Miami ranks near the bottom of the list for water availability, and scores high on vulnerability.
Unlike many other analysis, this study incorporated both local rainfall and the availability of stored and imported water – what the authors called 'hydraulic' sources. These sources include man-made reservoirs and aqueducts that can transport water from one drainage basin to another. The study also accounted for natural variability in rainfall and water availability to classify each urban area as low, medium, or high in vulnerability."

We really need drinking water.  We don't need to pollute it, then inject it deep underground where it can never be used again (aka fracking).  We don't really need green lawns for every home.  There are a lot of ways we waste clean water, and soon that luxury is going away.