It is quite literally everywhere. It covers 70% of the Earth’s surface and accounts for approximately 60% of our own composition. The thought that we could be running out of water seems unimaginable, and yet the combination of overuse, contamination, and the effects on the water cycle posed by climate change likely makes water the most unstable and therefore the most valuable resource of the 21st Century. The UN estimates that 3.4 billion people may suffer water shortages by 2025, and the problem stands to worsen from there forward.

Oscar-winning filmmaker Jessica Yu illustrates in her new documentary that water strains are fast becoming a vital concern not simply for a portion of the world’s population but for just about all of us. She recently spoke to Planet about directing “Last Call at the Oasis” and the things she learned along the way: