Matt Damon Uses Toilet Water For Ice Bucket Challenge

Have you done the ALS Association Ice Bucket Challenge yet?  And, if you did, would you have done it with a bucket filled with water (clean water, mind you) from the toilet? Well, after being nominated by Ben Affleck and Jimmy Kimmel, Matt Damon steps up and does exactly that. But what's with using toilet water?  I'm thinking the fact that Matt is a co-founder of the water.org site might have something to do with it...