Ever wondered what happens to the leftover soap and shampoo in your hotel's bathroom once you check out?
The remade soap, shampoo and so on is then donated to developing countries to improve hygiene and sanitation, as well as going to some local US women's, children's and homeless shelters.
Clean the World founder Shawn Seipler explained how the idea came around to Barb De Lollis of USA Today:
"We were business travelers. I spent 150-200 nights away. In a typical work week, I went to four different cities -- Monday, New York; Tuesday, Chicago, and Wednesday, Minneapolis."
After realising how much soap was being wasted, Seipler used to try to bring back soap and shampoos in his baggage to donate, but airport security liquid restrictions made carrying them on board impractical. So he started Clean the World.
The soap is collected in hotel housekeeping departments, brought to warehouses. The soap is then -- ironically enough -- cleaned, then repackaged for distribution.
Soap may sound like a small thing, but handwashing with soap is key to reducing child mortality in developing countries. With provision of clean water a more common activity for international development organisations, ensuring adequate supplies of soap is sometimes forgotten.
United Nations body Unicef's Therese Dooley, Senior Advisor for Sanitation and Hygiene, explains: "Handwashing with soap and water is a very ordinary act with extraordinary results for children's health, growth and development."
Unicef estimates that handwashing with soap could help save two-thirds of the 3.5 million children under five who die of preventable diseases every year. Preventing those deaths is part of the Millennium Development Goals for 2015.
With hundreds of hotels -- including many business hotels frequented by international travellers -- signed up to soap recycling programs, that goal looks a little bit closer.