I would agree. Oil only exists in certain locations and is extremely difficult to get, so it necessarily has to be extracted by corporations and shipped around

I would agree. Oil only exists in certain locations and is extremely difficult to get, so it necessarily has to be extracted by corporations and shipped around the world. Water, on the other hand, covers a lot of the surface of the planet, and even if you're not standing by a lake or river almost anyone can dig straight down and with an hour or so of work you're likely to find water. The places where this is not true are fairly rare, and the easier solution is to move the people to where water is instead of moving water to where people are. Filtering water to be drinkable is just so much easier than getting crude oil out of the ground. And worst case scenario, even if you have to move water from one place to another because the best farmland doesn't have water, basically anyone with a tanker truck and a hose can supply water pretty cheap. There's just not enough barriers to entry in the water business. The only way I see water becoming more valuable than oil is if oil demand falls so far that it's practically worthless.