I think that in the future, wars will be over water, too. There are places in the world that don't have enough water for everybody, so one half of the city gets water one day, and the other half gets water the next day and they alternate.
I think Jordan is one of those places, but I could be mistaken. I know it's somewhere in that area. I read about it in the book "Blue gold", and my environmental science teacher in college also went there and he told us about it.
Actually, some areas in Canada are starting to run low on clean drinking water because they've started to take groundwater and it can't be replenished as fast as they're taking it. (Groundwater moves very slowly. It's measured in feet or meters per year).
A really good book on it is "Blue Gold: The Fight to Stop the Corporate Theft of the World's Water".
People in North America use more water than anywhere else on the planet, and that needs to stop. A lot of it is for food production (because North Americans eat so much meat), but a lot of it is also used in the home - flushing toilets, showering, watering lawns, washing cars, filling pools, etc.
People in North America need to learn how to conserve water. Now is the time, while we still have it to conserve.