Please answer the following question: I know that the answer to the question "How does the sun come into contact with bottles when using SODIS?" is in "Solar water disinfection (SODIS) involves exposing water-filled plastic polyethylene terephthalate (PET) bottles to sunlight for several hours. Exposure times vary depending on weather and climate from a minimum of six hours to two days during fully overcast conditions. It is recommended by the World Health Organization as a viable method for household water treatment and safe storage. Over two million people in developing countries use this method for their daily drinking water.". Can you tell me what it is?
Answer:
exposing water-filled plastic polyethylene terephthalate (PET) bottles to sunlight