Clean Water Is The World's Greatest Challenge
"Pick a crisis any crisis the world is facing today: civil war, famine, AIDS, malaria, land mines. All pale in comparison with the problem we face regarding water... The problem is huge, but relatively cheap, low-tech solutions are available... We are not talking here about luxury service. Simply the bare minimums drinking water that is free from parasites and bacterial agents, and in terms of sanitation, just basic cesspits, what we would call an external latrine and which most of us would hesitate to use."
Thanks to Chris Steins