World Toilet Day: 1.5 Million people still don't have access to a clean toilet

The United Nation's World Toilet Day serves as a reminder that sanitation is one of the planet's greatest unmet challenges.

An estimated 2.5 billion people-one in three of the world's population-do not have access to a safe, private toilet, according to the charity WaterAid, which also estimates 500,000 children die each year from diarrhea caused by unsafe water and poor sanitation.

In sub-Saharan Africa, where the UN said a quarter of the population defecate outside, diarrhea is the third biggest killer of children under five years old. 

Studies estimate that a child dies every 2.5 minutes because of unsafe drinking water, poor sanitation and hygiene, the report said.

Women suffer most from the lack of facilities, with girls often denied schooling because of a lack of toilets, said UN Deputy Secretary-General Jan Eliasson.

"Girls are more likely to drop out of school if they don't have access to a safe and clean toilet. Women and girls can also risk harassment and sexual abuse when trying to find somewhere to defecate in the open. Universal access to sanitation has a clear role to play in defending women's safety, dignity and equality," he said.

Globally, an estimated 1.8 billion drink fouled water that's faecally contaminated, according to World Health Organization/UNICEF figures.

From 1990 to 2012, 2.3 billion people around the world gained access to an improved drinking-water source, according to UN-Water data.

India's 50 percent open defecation rate in contrast trails a 3 percent rate in Bangladesh and 1 percent in China, according to a May report by WHO and Unicef.