Water Bottle Lights? Yes, Really!

We should never take lighting for granted. In some countries, the cost of running lights can be prohibitive. In the UK, low energy, long life LED light bulbs keep these costs down. But in poorer parts of the world, people need even cheaper and simpler technology.

The history of lighting is a story involving fire, gas and electricity. The culmination of this story is LED lighting. Some countries, however, are unable to benefit from technological progress and LED light bulbs. The Philippines is a good example. The country has electricity, but it’s the most expensive in Asia. Many people have to do without light in their homes.

Fortunately, a local entrepreneur has found a cheap and simple lighting technology. It’s not a direct alternative to LED lighting because it doesn’t involve electricity. Instead, it uses plastic bottles, water and a drop of bleach.

The litre of light

LED light bulbs make efficient use of electricity. Water can make efficient use of sunlight. It can refract the sun’s beams into a dark room and provide light equivalent to that of a 60-watt bulb.

To achieve this, water must be in a suitable container such as a clear plastic bottle. A simple step-by-step process follows:

A metal worker cuts a circular hole the diameter of the bottle in a small square of corrugated tin.
The bottle fits three-quarters of the way into this hole and stays there, held fast by the surrounding tin.
A builder cuts a hole the diameter of the bottle into the roof of a home.
The householder fills the bottle with water, adds a little bleach to keep algae at bay, and suspends the bottle through the hole in the roof.

The sunlight hits the exposed top of the bottle. The water refracts the light down into the room beneath the roof. The result is a light source costing no more than a dollar. This technology, known as the Litre of Light, is spreading fast. The context is certainly different to our use of LED lighting; but what matters is the improvement in people’s lives.