Plastic bottles bring light to Philippine slums

A plastic bottle filled with water can become a source of lighting for slum homes in the Philippines, according to this video article on the BBC.

Recycling empty polyethylene terephthalate (PET) bottles by filling them with water and a drop of bleach, to prevent algae, creating a metal collar and inserting them in the roof can provide as much daytime light as a 60 watt bulb. The water-filled bottle refracts the sunlight into the windowless shacks, at a cost of about one US dollar each.