This sobering documentary addresses a number of problems concerning the global supply of freshwater, concluding that long-reliable sources are rapidly becoming undrinkable due to pollution and climate change, and that people are misusing many of the clean sources that still exist. Director Jessica Yu (In the Realms of the Unreal) can be unfocused in her approach, shifting haphazardly between multiple subjects without getting too deep into any of them, but given the enormity of the issues at hand, it’s easy to forgive her of overreaching. Though generally pessimistic, the movie still contains a few glimmers of hope, noting the efforts of scientists, farmers, and public health activists to influence policy reform.