Write the next sentence in the following story.

How to sterilize water with sunlight
Clean the bottle.
Remove anything in the bottle like dirt and on the bottle like a label. This method works with pet bottles (the clear/uncolored plastic bottles often used for mineral water or soft drinks and soda) and certain kinds of glass bottles.
The use of pet bottles for this process has been researched and found to be safe when used correctly. Because not all types of glass allow for the transmission of uv rays, pet is often recommended over glass, especially since plastic bottles are also less breakable and cheaper.