"Regardless of the climate zone, a human needs to meet a certain level of water intake daily."

http://www.practicalsurvivor.com/emergencywaterfiltration

Half your body weight in ounces of water is a good and easy minimum to maintain.  Ex:  150 lb person would need to consume ~75 oz/day to maintain a "healthy" optimum.  Sounds like a lot?  It isn't.  If it really seems like too much, get close and you won't regret it.

There are many sites to choose from.  I've made and practiced making some of these DIY water filters and have taught others to make them for themselves.  If you start now, when the time comes, you'll already have enough for yourself and can help your neighbors to make their own.

Lots of other sites on YouTube, etc.  He ka waiola!  Ae?

https://www.nbcnews.com/storyline/puerto-rico-crisis/half-hurricane-ravaged-puerto-rico-faces-lack-fresh-water-n805346