It weighs no more than 300 grams, fits easily into a backpack and looks like any other plastic bag.
But the simple device is a life-saver for people who have no access to clean water.
The bag, called FieldtrateLite, filters dirty water, such as river water, through ceramic membranes and turns it into portable water.
It is the brainchild of Singapore social enterprise WateROAM, which is run by four young people - David Pong, 26, Lim Chong Tee, 24, Vincent Loka, 22, and PooiChingKwek, 27.
FieldtrateLite, which costs $35, does not require electricity and can last three to five years.
It takes just an hour to filter a full bag of six to 10 litres of water. WateROAM also has a more elaborate Fieldtrate Plus system, which can produce up to 500 litres of clean water per hour.
To date, its filtration systems have provided drinkable water for some 1,000 people in three countries, including a village in Phnom Penh, Cambodia, and victims of last December’s floods in Kelantan, Malaysia.
Currently, a prototype of Fieldtrate X, which can filter water containing arsenic, is being tested by the Bangladeshi government.
According to Mr Pong, WateROAM’s chief executive: “Our vision is to build a world where no person shall face prolonged thirst.”
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