For every $1 invested in water and sanitation, an average of at least $4 is returned in increased productivity.
(Hutton, Global costs and benefits of drinking-water supply and sanitation interventions to reach the MDG target and universal coverage, WHO, Geneva, 2012: page 4)

Every year, around 60 million children are born into homes without access to sanitation.
(UNICEF, 2006 - Progress for Children)

Around 315,000 children under-five die every day from diarrhoeal diseases caused by dirty water and poor sanitation. That's 900 children per day, or one child every two minutes.
(WHO/UNICEF 2015)