Here's an extract on this topic from a fantastic book called 'Poor Economics': Most experts agree that access to piped water and sanitation can have a dramatic impact on health. A study concluded that the introduction of piped water, better sanitation, and chlorination of water sources was responsible for something like three-fourths of the decline in infant mortality between 1900 and 1946 and nearly half the overall…
http://www.amazon.com/Poor-Economics-Radical-Rethinking-Pove... Would be interested to hear about any similar books you'd recommend.
By the way, Esther Duflo (co-author of the book) has a TED talk worth watching: http://www.ted.com/talks/esther_duflo_social_experiments_to_...