These solar-powered sanitation systems – championed by Bill and Melinda Gates’s Reinvent the Toilet Challenge – promise to solve one of the greatest dilemmas for infrastructure-challenged regions such as India.

At this month’s Greenbuild conference, the Kohler exhibit included a miniature version of its collaborative project with the California Institute of Technology: a brightly painted, photovoltaic toilet prototype that uses internal purification systems to allow water reuse, without wastewater disposal. In 2012, the concept won first prize and $100,000 during the inaugural Reinvent the Toilet Challenge, a competition developed by the Bill & Melinda Gates Foundation to fund affordable, sustainable sanitation solutions – especially those that function off the grid, without power or water connections.

In the competition’s first year, grants worth a total of $3.4 million were awarded, including nearly $780,000 for a team from University of Colorado Boulder, which developed a toilet using a focused solar dish to disinfect and “cook” waste, producing biological charcoal (biochar) – a wood charcoal or chemical fertilizer replacement. Eram Scientific Solutions, based in India, was also awarded more than $450,000 to produce its solar-powered eToilet; since then, more than 600 units have been installed throughout the country, with more than 200 located in schools.

This year’s Reinvent the Toilet competition was co-hosted and co-funded by the Government of India, with a total of $2 million awarded during a fair that hosted more than 45 exhibitors, representing 15 nations. Six winners were chosen from 108 entries; finalists included a modular electronic toilet for houses, in-toilet ultrasound systems to reduce water use and biologically based trials to control odour and minimize waste output. Similar initiatives are underway in China and South Africa, which will invest almost $4 million in field-testing new ideas.

It’s a worthy cause: more than 40 percent of the world’s population, or approximately 2.5 billion people, lack access to adequate sewage disposal. In many cases, septic systems are over capacity, or raw sewage is siphoned directly into the environment.

One of the most disadvantaged countries in this respect is India, with more than 640 million people using only the most basic toilet facilities, if any at all. With an estimated 72,000 tons of untreated human waste per day, a lack of adequate sanitation significantly contributes to the spread of disease in the country; each year, intestinal malaise causes approximately 700,000 fatalities among children.

In recent news, India’s Prime Minister Narendra Modi launched the “Clean India” movement in honour of Mahatma Gandhi, who said that “sanitation is more important than independence.” This September, the Washington Post published an editorial, authored with U.S. President Obama, in which PM Modi committed to “leverage private and civil society innovation, expertise and technology to improve sanitation and hygiene throughout India” – signifying a new era for a country that has struggled to clean up its reputation for inadequate hygiene.