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It's World Toilet Day today - not as much a celebration of the porcelain throne as a call to action to help the 2.5 billion people worldwide who do not have access to a basic, clean toilet.

One in three people around the world do not have access to proper sanitation, according to the United Nations, putting many of them at risk of diseases such as diarrhea, cholera and typhus, and a host of other health problems.

About 2 million people - many of them young children - die every year from diarrheal diseases, according to the World Health Organization. Almost 2,000 children die every day from preventable diarrheal diseases - 760,000 children total in 2011, according to UNICEF.

Recycling Urine Into Drinking Water in Space

The United Nations established World Toilet Day this year to spark movement on sanitation-related issues, like improving the water supply in developing areas and changing the behavior of the billions of people who don't have a safe place to relieve themselves.

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As populations in developing countries shift from rural to urban areas, people have increasingly packed city slums that aren't equipped with sewage systems, latrines, basic toilets or readily available clean drinking water, according to William Moomaw, a professor of international environmental policy at the Fletcher School of Law and Diplomacy at Tufts University, in Medford, Mass.

"It's literally like walking around in a cesspool, with the amount of waste that's produced," Moomaw told ABC News. "The waste is just flowing in the streets in some of these places."

Sub-par sanitation often creates contaminated drinking water and, when facilities aren't safe, can put women and disabled people at risk of sexual violence.

And the economic impact is severe, according to the World Bank. It estimated economic losses stemming from lack of access to sanitation at $260 billion annually.

Cleaning Up the World's Sanitation

On a more personal scale, farmers and others who don't have a clean toilet can contract a waterborne disease and stop contributing economic output, Moomaw said. "You can't farm if you're sick," he said.