A boy drinks water from a pipe, in a rebel-held town of Douma in Syria on June 23, 2016. [Photo/VCG]

About 650 million people, or one in 10 of the world's population, have no access to safe water, putting them at risk of infectious diseases and premature death. Dirty water and poor sanitation can cause severe diarrhea in children, killing 900 under-five-year-olds a day across the world, according to United Nations estimates. World Water Day, marked this year on March 22, highlights various concerns about the world's water resources.