There is desalinization in scale, it is called water cycle, powered by free solar energy. Hundreds is a large number to brain yet small number to practice.
Discussion
It is a lot. But if you need water, are you going to depend on the rain cycle? Hope is not a good plan. Good luck with that.
Not enough to make up what has been lost, and not enough to fight a wild fire. You don’t know how powerful a forest fire is. Hope is not a good plan, using water plant to fight a forest fire is neither. Good luck to both.