Though it includes such ideas as a solar-powered commode that runs without water, the 2007 World Toilet Summit is no bathroom novelty show.

Participants at New Delhi's four-day gathering of experts, toilet aficionados, and even royalty from 44 countries are grappling with health and sanitation issues that endanger almost one-third of the world's people who don't have toilets.

The United Nations estimates there are some 2.6 billion people without access to basic sanitation, over half living in India and China, a stark reminder of the challenges facing these developing nations despite their recent rampant economic growth.

"In India there are 700 million people who do not have access to safe and hygienic toilets. The waterborne diseases this causes kill 500,000 children every year, mostly from diarrhea," said Bindeshwar Pathak, the head of the Sulabh Sanitation and Social Reform Movement.

The theme of the seventh annual toilet summit — co-hosted by Pathak's group, the Indian government and the Singapore-based World Toilet Organization — is reaching the U.N.'s goal of halving the number of people living without water and sanitation by 2015.

With India hosting the event, it also focused on a unique local problem.

Euphemistically known as "night soil workers," an estimated 500,000 people — most of them "untouchables" from the lowest rungs of India's complex caste system — still work cleaning out human excrement from dry latrines.

"I was married when I was 10-years-old, since then I have been doing this work," said Usha Chaumar, 30, a woman from the western state of Rajasthan describing how she would descend into the latrine pits early in the morning and carry out the fresh waste in a bucket on her head.

Chaumar would clean 15-to-20 of these latrines daily, paid $0.25 per toilet per month.

"The people would throw the money on the floor so they would not have to touch me," said Chaumar who is now in a training program run by the Sulabh group to change her hereditary profession.

For generations, the caste-system's strict social order dictated what work people did, who they married, where they lived and even who they shared a meal with. For "untouchables" like Chaumar it meant a life doing what her ancestors had done and the diseases that accompany it.

"Now I am not untouchable, I am also a person, a good person," she said, talking about her business selling pickles and her new life attending summits with royalty and presidents

Dutch Crown Prince Willem-Alexander who chairs the U.N. secretary-general's advisory board on water and sanitation, was the guest of honor at the summit, while former Indian President A.P.J. Abdul Kalam opened the event.

India's Rural Development Minister Raghvansh Prasad Singh told the conference that India was investing $3.45 billion in sanitation projects including rehabilitation and self employment schemes for people like Chaumar.

Part of the problem is building expensive sewage systems in remote rural areas with scarce water supplies.

"Sewage systems are essentially 19th century technology, we need modern solutions," said Pathak.

That is where toilets like the one being promoted by the company African Sanitation come in. Pioneered for the slums of southern Africa, it requires no plumbing, no water and almost no maintenance.

Once a week a tray below is emptied of waste, now turned into an almost odorless compost by a solar heater and natural bacteria.

Talking to the toilet experts — including a group of deeply earnest 12-year-old Indian school children who spend their weekends working with their school's "sanitation club" — can be a sometimes-surreal expedition through technical aspects of personal hygiene and cultural differences inherent at a global toilet summit.

As African Sanitation's Lukas Oosthuizen discovered, their model needed a minor addition of a water tray to the design before it could be effectively deployed in India.

"We discovered that people here are washers, not wipers," he said.