Solar water disinfection

Imagine that you have a glass of water with some germs in it. You can't see them, but they're there. Now imagine that you put that glass of water in the sun and leave it there for several hours. When you come back, the water is safe to drink! That's what solar water disinfection is all about.

When we use the sun's energy to disinfect water, we're relying on two things: heat and UV radiation. UV radiation is the same thing that gives people sunburns, but in this case, it's actually helpful! When water is exposed to UV radiation, it can damage or kill the germs that are in it. The heat from the sun helps to support this process because it helps to speed up the chemical reactions that happen between the UV radiation and the water.

To use solar water disinfection, you need a clear plastic bottle or container, like a soda bottle. You fill the container with water, leave some air at the top, and then set it out in the sun for at least six hours. Ideally, the container should be placed on a dark surface so that it absorbs more heat from the sun. It's important to also make sure that the container is not shaded by anything, like trees or buildings. The more direct sunlight it gets, the better.

After six hours in the sun, the water is safe to drink! The germs have been killed by the UV radiation from the sun and the heat has helped to speed up the process. Solar water disinfection is a simple and effective way to make drinking water safe without using any chemicals or fancy equipment.