You are half right. We are running out of "cheap" drinking water. The absolute supply of water never changes and there are parts of the world with so much freshwater they don't know what to do with it... while others experience shortages.

Let's look at my state, southern California is in the middle of extended drought (happens periodically). Meanwhile, just one river in Alaska dumps enough freshwater into the Pacific every day to more than make up for all of California's water shortage. In addition, poor water management accounts for California losing about a third of its freshwater to "leaks" and evaporation in its freshwater systems.

So let's translate that... we could adopt an Israeli strategy that only needs 10% of their freshwater to come from "nature", the rest is recycled. Or we could trade Canada... let them have the Keystone Pipeline in exchange for allowing the US to pipe water down from Alaska to the US west coast. Win win... lower energy costs and more fresh water for drought starved California... more high paying pipeline jobs and economic growth... but of course, these things are not important... yet!.