For this to work properly, you must use a clear and clean plastic water bottle. It is recommended that the plastic be “PET” (polyethylene terephthalate). You can identify this type of plastic because it will have a recycle number of 1 on the bottle. The bottle should be no larger than two liters.PET is a very common plastic used in the manufacture of most soft drink and water bottles.
The bottle should not be colored at all.
 In order to sanitize the water with UV from the sun, the water itself must be clear. If there is any sediment in it, the UV will be less effective. Place a cloth over the top of the bottle and pour the water through the cloth. This will capture any sediment and make the water clear.This filtering step will not sterilize or purify your water, it will just remove the solid particles that may be suspended in the water.
 The sun emits UV rays and therefore can be used for sanitization. The absolute minimum amount of time required for sterilization is six hours. This is the minimum for a bright, sunny day. Most microorganisms will be killed in this amount of time with the exception being cryptosporidium (10 hours is recommended). If the sky is partly cloudy or half-filled with clouds it can take up to two days for sterilization to be complete.Make sure the bottle is on its side and not standing upright. This will maximize the UV exposure.
Increase UV exposure by placing the bottles on top of a reflective surface such as foil.
Obtain a clear, plastic water bottle.
Filter the water.
Lay the bottle in the sun for at least six hours.
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