Jimmy Kimmel and Ben Affleck nominated Matt Damon for the ALS Ice Bucket Challenge, but seeing as the Oscar winner runs Water.org, he had some reservations about wasting a whole bunch of H2O.

It posed kind of a problem for me, not only because there is a drought here in California, but because I co-founded Water.org, and we envision a day when everybody has access to a clean drink of water, Damon says in the video above. There are about 800 million people in the world who dont, so dumping a clean bucket of water on my head seemed a little crazy.

Matt's solution? Take it from the toilet bowl! "For those of you, like my wife, who think this is really disgusting, keep in mind that the water in toilets in the West is actually cleaner than the water that most people in the developing world have access to," he continued. "So as disgusting as this may seem, hopefully it will highlight the fact that this is a big problem and together we can do something about it."

Damon then nominated pal George Clooney, U2 singer Bono and Tom Brady. But Matt's not the only one who has pointed out that we're wasting water with the challenge! Kristen Stewart and co-star Nicholas Hoult used dirty bath water for their ALS challenge last week, and the other day Jeremy Renner did his in a kiddie pool with his daughter.