For Niihau island...

UC Berkeley Researchers have discovered a way to convert water from air using solar energy.

This is ideal for Niihau and other Desert Regions that have little or no water. 

Niihau has no waterfalls or rivers, and its "lake" is a puddle except when it rains, which is rare.

Nearby Kauai is the "2nd wettest place on Earth" so extracting air from the region will benefit Niihau residents.

M7 2017.

http://us.blastingnews.com/tech/2017/04/uc-berkeley-researchers-find-new-way-to-extract-water-from-the-air-001630665.html