The world’s supply of cheap and clean fresh water will likely plummet as the climate warms and populations boom. Can we find ways to conserve, cut waste, and find new sources before it’s too late?

The latest installment of our What Happens Next series looks for solutions in an unlikely spot: a city perched on the edge of the world’s oldest desert. For the residents of Windhoek, Namibia, the arid future arrived long before the growing freshwater crisis made headlines around the world.

And this city responded to worsening cycles of drought by tapping water resources from a radical source that was already on hand: wastewater from their own city sewers. And while the technology for building a toilet-to-tap management system isn’t new, the mindset required to do here offers a lesson to any city facing an increasingly arid future.