Greg Allgood tears open a small sachet and dumps the powder into a large plastic container filled with brown, murky water. After about five minutes of stirring, clumps of sludge form and sink to the bottom as the water starts to clear.
"You let it settle, pour it through a cotton cloth and then you wait 20 minutes and it's ready to drink," said Allgood, the US-based director of Procter & Gamble Co's not-for-profit programme to provide clean water in developing nations and disaster zones.
"We reverse engineered a municipal water treatment plant, so something that costs tens of millions of dollars we can make for three and a half cents."
P&G, a consumer products giant, works with international and local humanitarian groups such as Care, World Vision and Save the Children to get the sachets to areas where dirty water is a leading cause of illness and death.
One sachet purifies 10 litres (2.6 gallons) of water, enough for five people for one day, and it does not matter that the container and straining cloth are not clean. Shipping, duties and distribution, education and training by the groups on the ground take the final cost to about 10 US cents per packet.
The dirt in Allgood's demonstration came from his garden, where his dog likes to romp. Iron sulphate is the coagulant that pulls together soil, heavy metals and parasites. Chlorine - a precise 80 granules per sachet - kills viruses and bacteria, including those that cause cholera.
"When the water is really dirty, there aren't a lot of low-cost technologies that work very well," Allgood, who has a PhD in toxicology and is P&G's point person in the Clinton Global Initiative, told Reuters in an interview before the formal opening of a new production plant in Singapore on November 29.
"It seems strange to us but I hear it so many times - people see this and they say 'Oh my God, I was drinking dirty water'."
About 40 million sachets will be made this year at a plant in Pakistan and 100 million in Singapore, which is also P&G's global disaster relief hub. The goal is to make 200 million a year by 2020, equal to 2 billion litres of clean water.
Many of the sachets are sent to development projects in Africa and emerging Asian countries but were also handed out to people hit by floods and other disasters in Pakistan, Thailand, the Philippines, Indonesia and Haiti, Allgood said.
Clean water is also vital to people with HIV/AIDS, he added, as their damaged immune systems make them very vulnerable to life-threatening diarrhoea and other infections.
"It goes well with Scotch," Allgood joked, handing over a glass of clear, clean water that had been dangerous to drink 30 minutes earlier and now had only a slight taste of chlorine.
In Haiti after the devastating earthquake of 2010, he said, the sachets were part of relief supplies and he visited tents for cholera victims, showing aid workers how the powder works.
"I grabbed a bucket out of the place where the effluent was from where they washed the clinic. I went and treated it and told the World Vision folks we had to drink it," he said. "They looked at me like I was crazy. But we did drink it.