An Indian girl holds a can filled with water and walks past railway tracks to defecate in the open in Mumbai, India,

"Those who make do without toilets continue to pollute water sources and jeopardize public health and safety for millions worldwide. That contributes to malnutrition and childhood stunting, impairing 161 million children both physically and mentally every year.

"Until everyone has access to adequate sanitation facilities, the quality of water supplies will be undermined and too many people will continue to die from waterborne and water-related diseases," WHO's public health department director, Dr. Maria Neira, said in a statement."