For more than two years, Kohler Co. has collaborated with Caltech in the development of a photovoltaic toilet as part of the Reinvent the Toilet Challenge, hosted by the Bill & Melinda Gates Foundation. In response to this successful project, the Gates Foundation recently approved a two-year grant to Kohler to design and fabricate five closed-loop flush toilet systems for field testing in developing world locations without adequate sanitation.

With the recent announcement from India’s Prime Minister Narendra Modi, promising through his Swachh Bharat Abhiyan (Clean India campaign) to build 100 million toilets across the country, global interest in the developing world’s sanitation conditions is higher than ever. 

“There are 2.5 billion people in the world without access to adequate sanitation,” said Rob Zimmerman, sustainability manager for Kohler Co. “While education is an issue, there is also the need for sanitation facilities that are hygienic, cost-effective and provide an aspirational toileting experience.”

The prototype unit developed by the Kohler-Caltech team was displayed in March 2014 in Delhi, India, at the Reinvent the Toilet Fair — a showcase of the projects funded through the Reinvent the Toilet Challenge — and is currently in field-testing in India. Kohler will use the field findings to further improve the system, with the goal of making it a more transportable unit. The toilet system includes a self-contained water purification and disinfection system that allows water to be reused and does not require wastewater disposal.