PETE bottles: How can I tell which are which?

I reuse certain plastic bottles to store food products and water.  Located on the bottom of the bottle is a triangular symbol.  The letters "PETE" are imprinted underneath the triangle.  I think this labeling indicates the plastic is less porous than other types of plastic.  It keeps out oxygen better. Check out the info on the link regarding which plastics are safe for food storage: http://extension.usu.edu/htm/news/articleID=3575