The challenge
Having a clean, sanitary system to dispose of human waste saves millions of lives a year, without most of us even realizing it, because the consequences are dire in places where such systems don’t exist.
About 2.5 billion people don’t have access to safe sanitation, especially in sub-Saharan Africa and Southeast Asia, according to the World Health Organization, and every year, lack of proper sanitation kills 300,000 children under the age of five, mostly from diarrhea, according to the World Health Organization.
But building complex, sanitary sewer systems is intensive — and expensive. A better solution is now available, thanks to Hertz Fellow Ruby Lai.
The solution
In 2011, Lai took part in the Gates Foundation’s Reinvent the Toilet Challenge, looking at how bacteria could be supercharged to handle waste.
That jump-started Lai’s work in this field. In 2025, thanks, in part, to a $25,000 grant from the Hertz Foundation’s Harold Newman and David Galas Entrepreneurial Initiative, she launched Foss Toilets. The sewer-less toilet systems could “help address sanitation access around the world, which is a major killer that provides a transmission route for dangerous communicable diseases,” she said.
It can also reduce water usage in places where sewers already exist, but water is becoming scarce. “Our toilet system uses no outside water, so it can really put a dent in water use, which is a growing issue in the dry, drought-prone Western United States,” Lai said.
“A sewer-less toilet system could help address sanitation access around the world, which is a major killer that provides a transmission route for dangerous communicable diseases. Our toilet system uses no outside water, so it can really put a dent in water use, which is a growing issue in the dry, drought-prone Western United States.”
Ruby Lai
Founder, Foss Toilets
the impact
Foss Toilets has tested its energy-efficient and low-cost water treatment system prototypes, which enable the cleaning and reuse of sewer water. Another fully automated prototype will be tested at Duke University.
“Just being able to learn from the experiences of other Hertz Fellows, and see that other fellows have successfully pursued off-the-beaten-path ideas, really gives me an example of what I can achieve, and the confidence to follow through on my ideas,” says Lai.
