>The real issue with dams is the scale. I couldn't agree more. >I agree; however, this is not an infinite supply. Well no system can provide an infinite supp

>The real issue with dams is the scale. I couldn't agree more. >I agree; however, this is not an infinite supply. Well no system can provide an infinite supply, but rainwater harvesting could support the current human population at a first-world standard of living (something our present system does not provide). Many areas famous for recent crippling droughts suffered from flooding only months before. This is a spectacular failure in water management. As to cost, I haven't seen any comparisons of the lifetime cost of rooftop rainwater harvesting vs centralized pumped underground pipe distribution. I know rainwater harvesting is much more common in Australia, so they might have more data. I suspect it's strongly dependent on the cost of energy. One thing I forgot to mention about desalination: current technology (specifically the Affordable Desalination Collaboration’s pilot plant) is at 30% of the thermodynamic limit. So we can expect a 3x improvement in performance, but no more. http://www.usbr.gov/research/AWT/energy_use.html http://www.usbr.gov/research/AWT/energy_use.html