for me in acting. >> reporter: worldwide, more than 750 million people live without poetable water, making them susceptible to disease. since 2009, water.org has helped communities connect to clean water through wells and microloans. the founders say their approach isn't just charity but a sustainable solution. >> tell me about the water credit. how does it work? >> so, if you're in a slum in india, you might be spending hours every day walking to a public tap, waiting in line. the water's sometimes there, sometimes it's not. you might be paying the water mafia, which is basically these people who come around and sell you 20 liters of water for a pretty high price. >> if you could actually just front them the money to connect to the municipality that was piping water right underneath their feet, you'd give them their time back so they could work at their job and pay the loan off. >> reporter: this isn't a glamorous topic to discuss at hollywood fund-raisers, but matt damon has not shied away. >> until everybody has access to clean water and sanitation, i will not go to the bathroom. >> reporter: earlier this year, he launched a spoof campaign with fellow celebrities to bring