The Freakonomics Blog has a really interesting post for World Water Day about how chlorine is a simple action that can help provide safe water.

Diarrheal diseases claim two million lives each year worldwide—a loss that is especially tragic because it is so needless. There is a cheap, highly effective ways to treat and prevent diarrhea, but it is woefully underused. Chlorine—dilute chlorine solution for drinking water, to be precise. Just a few drops of chlorine will reliably eradicate diarrheal bacteria from ten to twenty liters of water, even in a dirty container. It’s powerful stuff.

The post goes on to discuss how chlorine use can be increased and what lessons were learned from a project run by GWC member Population Services International (PSI). 

The authors found some interesting things about the first two interventions — village-wide marketing worked slightly better than one-to-one, and community leaders’ chlorine usage appeared to influence other people’s decisions somewhat — but they only led to small and short-term increases in overall usage. Having a local promoter drawn from the village itself, on the other hand, drove up usage both immediately and persistently.

It’s definitely worth a read so take a look at their entire post.