The Sport Berkey Water Bottle is made of safe, non-leaching, BPA/BPS free low density polyethylene (LDPE recycle code #4). The cap is made of high density polyethylene (HDPE recycle code #2). The straw is made of polypropylene (recycle code #5).
The number on the bottom of the bottle is not to be confused with the recycle code. The bottom of the bottle will be labeled with the diescast (molding) number. This will vary from 1 to 4.
LDPE is used for the bottle for its "squeeze" properties. LDPE is a very effective moisture barrier and is widely used for bread bags, trash/leaf bags, mustard and honey bottles, frozen food bags, tote bags, clothing, furniture, dry cleaning bags, and carpet.