How Do I Use Solar Power to Purify Water? by Jessica Blue, Demand Media

Choose a clear plastic bottle and remove all labels for a simple water-purification method.

Even when it looks clear, water can carry hordes of microscopic germs — bacteria and viruses that can wreak havoc on your body. Drinking water is normally sanitized at treatment plants before it enters the home, but if you're camping or drinking water from a rural well, for example, you're not drawing water from the typical water purification infrastructure. You can still protect your gut, though, with a simple water-purification method. This approach is similar to boiling water, though it is more effective because along with heat it uses a spectrum of UV-A light that kills many pathogenic microorganisms . However, it does not fully clean very muddy water or water that contains toxic chemical pollutants.

Items you will need:

Plastic bottle with recycling code 1 (PET/PETE)
Funnel
Piece of clean cloth, such as an old T-shirt
Cup or bucket

Step 1:
Wash and dry a plastic bottle and remove all labels. The bottle should be clear to let in as much light as possible.

Step 2:
Choose a relatively clear section of water if you are gathering water from a stream. Mud and other floating matter can detract from this method's effectiveness.

Step 3:
Remove the bottle cap and place the neck of the funnel into the mouth of the bottle. Stretch the cloth across the funnel and tie or hold it in place. The cloth filters particulate matter from the water.

Step 4:
Scoop up some water with a cup or bucket and pour it slowly over the cloth into the funnel.

Step 5:
Stop filling the bottle when it is 75 percent full. Replace the cap.

Step 6:
Shake the bottle vigorously for about 20 seconds.

Step 7:
Place the bottle horizontally on a flat surface like a rock or a rooftop. Ideally, the surface should be dark or reflective. Corrugated tin roofs work best, but any surface works as long as it receives direct sunlight.

Step 8:
Let the bottle sit for at least 6 hours. If the sunlight is indirect or the sky is cloudy, let the bottle sit for 24 hours.
From hermitjim.blogspot.com