Polyethylene Terephthlate (PET) Water Bottles

The PET bottle exceeds the HDPE bottle in strength, toughness, and clarity. Filled 1.5-liter bottles dropped on concrete from a height of 6 feet have a survival rate greater than 97 percent (Hanlon, 1992). The toughness of PET also allows production of bottles with a wall thickness ranging from 0.010 to 0.020 inches.

PET water bottles are designed for portability, with gripping ribs on the bottle's lower portion reducing slippage. Popular sizes are 0.5, 1, and 1.5-liters (16.9, 33.8 and 50.7 fluid ounces respectively).

Quality Concerns
Disadvantages of PET water bottles are shrinkage and taste problems. The empty bottle shrinks if exposed to a temperature around 900 (19SF) (Hanlon, 1992).

At the modular facility, monitor the mold's temperature settings to achieve good bottle perpendicularity and wall thickness distribution.

At the bottling plant, new bottles should be stored away from heat generating sources and sunlight. Acetaldehyde, which is found in trace amounts in PET bottles after production, affects the taste of the water content especially when the bottles are exposed to elevated heat. Tests show the presence of a slight fruity taste from a PET bottle which was stored at 490 (120F) for 72 hours. A similar taste was also observed from a year-old bottle stored at ambient temperature. The intensity of the taste varies among PET resins.

PET water bottles are packaged in corrugated boxes. Package sizes are twentyfour 0.5-liter bottles, twelve 1-liter bottles, and twelve 1.5-liter bottles. Warehousing practices are similar to those for HOPE water bottles: Two-pallet high, short storage time, and avoid exposing the product to heat.

The 28-mm crown caps are the standard closures of PET water bottles. Recently, a push-pull dispensing cap was introduced to enhance the package's portability.

There are variations in the dimensions of the bottle finishes, and variations in the caps as well, therefore, the fit between the two parts is sometimes unsatisfactory. It is necessary to monitor the capper for correct application torque and verify dimensions of bottles and caps regularly to ensure package quality.

An over tightened cap causes difficulties for consumers, an under tightened cap may not sufficiently protect the product during transportation and result in leakage.