I am going to stop you from getting fresh water johnny!
No please don't.
By my magical powers I've come back in time to explain the water cycle to you and tell you what im going to do to it.
First the water evaporates, then it forms into water vapor that condenses into clouds, then the clouds get so heavy that they start a process called precipitation. I would tell you more but I have to start my evil plan.
Now it is my time to start dumping the nucular waste that I found in this cave to pollute the water source here.