Reconsidering the components of a minimum water requirement estimate for human health and for economic and social development suggests that a country requires a minimum of 135 l/c/d. With all countries except Kuwait having much greater water resources than this, water scarcity alone need not hinder development.Although the discussion of water used for food production is stilted, he argues that agricultural water supplies can come from reclaimed water, i.e., adequate food can be produced by recovering about 70 lcd from wastewater flows.
Most of these numbers are based on water use in Israel. Although I have no problem with that, water distribution across geographic and economic sectors in Israel is less-complicated than in bigger countries. (Obviously, I am ignoring Palestine -- a HUGE complication that probably gets the short end of Israeli policy.)
Bottom Line: The full expression of economic and social development in urban areas can be achieved with as little as 135 lcd (or 36 gallons/capita/day) -- far less than my suggested 75 gcd "lifeline" water supply (for residential use only). Since we use much more than that, there's a good chance that urban conservation will not reduce our quality of life.