The film that inspired the issue of safe and clean water for me was FLOW: For Love of Water. Don't let the lack of polish and organization in this film slow you down-- the information conveyed is startling. Watch it, and like me, you will start avoiding bottled water and support the public water system.
Les Guthman responded to my call out to filmmakers who have films on the subject. He made The Hudson Riverkeepers and The Waterkeepers with Robert F. Kennedy, Jr. They are available on the XPLR channel on Snagfilms and DVD.
Guthman says, "The story of the 40-year fight to clean up the Hudson, in particular, is a seminal story in the history of the environmental movement in this country. The Hudson River Fishermans Assocation lawsuit against Con Ed in the 1960s went to the U.S. Supreme Court - and its decision in their favor paved the way for all of the environmental legislation of the 1970s - the Clean Water Act, Clean Air Act, Endangered Species Act, etc. The next 30 years on the Hudson are a powerful story as well. 'The Waterkeepers' profiles six river, bay and soundkeepers around the country, part of Kennedy's 'Waterkeeper Alliance,' which took the Hudson Riverkeeper model and spread it to fight water pollution around the world."
Laura Dunn's highly lauded, The Unforeseen, is worth a watch to see the story of Austin's Barton Springs via lyrical filmmaking.
Finally, in my online reserach I came across this PDF which lists several more pertinent films compiled by the Jane Goodall Institute.
Drill down into these links and you will see lots of ways to get involved in the essential human right of safe and clean (and free) water.