When it comes to water, cities have plenty to worry about. From sea level rise and flood to drought and contamination. For the dry, mountainous capital city of Yemen, Sana'a, it's the latter, as the city's water supply is quickly drying up.
Fortunately, one woman has a plan -- an award-winning plan.
Sabrina Faber's plan to harvest rainwater on the flat roofs of already existing buildings was the first-prize winner of the Philips Livable Cities Award, and received a grant of more than $100,000 to implement the plan.
See how her plan works:
The Philips Livable Cities Award received more than 450 entries from people with ideas of how to make life healthier and more sustainable for people living in cities. Many of the ideas were simple, but also practical and effective solutions that would be relatively simple for cities to implement. At the same time, the solutions would be a big improvement to the quality of life for people living in the city. Check out some of the other entries.