When an American student saw a Cambodian woman washing her child with detergent, he was horrified. But then he thought of a place he could get large quantities of soap free of charge. Two years later, he's already supplying villagers with a safe way to keep clean, and also with jobs.
Samir Lakhani was spending the summer building fish ponds in a Cambodian village when he saw the mother scrubbing the young child with laundry washing powder.
He was devastated, he says. Detergent can harm the skin, and contains toxic chemicals that can cause itchy eyes and vomiting. Hygiene is important to prevent disease, but this was not the way to clean a human being.
"Immediately, to any Westerner, it was like - this process and practice needs to be rectified - we need to do something about that," he says.
Then something clicked. The NGO he was working for, while taking a break from his environmental studies course at Pittsburgh University, was based in Siem Reap - a thriving tourist hub a stone's throw from the magnificent, 800-year-old temples of Angkor, which draw more than two million visitors a year...
With over 500 hotels and guesthouses to service them, Siem Reap produces a lot of leftover soap.
"There is probably no better place on Earth to start soap recycling than Siem Reap," says Lakhani.
He returned immediately to his hotel room, determined to find a way to do it.
"I purchased meat cleavers and meat grinders and cheese graters. I turned the hotel room into a laboratory. We had bubbling cauldrons. I was probably put on the watch list," he says.
He mugged up on chemistry, reached out to scientist friends, and soon emerged with a technique for combining discarded bars of soap into a new composite bar of "eco-soap".
"There is probably no better place on Earth to start soap recycling than Siem Reap."
From there things grew rapidly.
First he went to hotel to hotel, asking for leftover soap. The NGO he was volunteering with - Trailblazer Cambodia Organization (TCO) - put him in touch with local students to help with soap production, and provided space for them to work.
Once back in Pittsburgh for his final year of studies, he started crowdfunding. Then he succeeded in obtaining sponsorship from major hotel chains, to enable him to train and pay soap makers.