Over 2.4 million people worldwide are still without sanitation, including 946 million who are compelled to defecate in the open, a United Nations assessment said on Wednesday.
The assessment done by the World Health Organisation (WHO) and United Nations Children's Fund (Unicef) also warned that the lack of progress on sanitation is threatening to undermine child survival and health benefits from gains in access to safe drinking water.
The assessment -- Progress on Sanitation and Drinking Water: 2015 Update and Millennium Development Goals (MDG) Assessment -- was done to report tracking access to drinking water and sanitation against the Millennium Development Goals.
"What the data really show is the need to focus on inequalities as the only way to achieve sustainable progress," said Sanjay Wijesekera, head of Unicef's global water, sanitation and hygiene programmes, in a statement.
He said that the global model so far has been that the wealthiest move ahead first, and only when they have access do the poorest start catching up.
"If we are to reach universal access to sanitation by 2030, we need to ensure the poorest start making progress right away," he said.
"Although some 2.1 billion people have gained access to improved sanitation since 1990, the world has missed the MDG target by nearly 700 million people. Today, only 68 percent of the world's population uses an improved sanitation facility -- nine percentage points below the MDG target of 77 percent," said the report.
Maria Neira, director of the WHO Department of Public Health, Environmental and Social Determinants of Health, said that 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.
"The practice of open defecation is also linked to a higher risk of stunting -- or chronic malnutrition -- which affects 161 million children worldwide, leaving them with irreversible physical and cognitive damage," she said.
The report also said that United Nations General Assembly (UNGA) will set up the new sustainable Development Goals in September 2015 including a target to eliminate open defecation by 2030.