Does PET lightweighting really reduce the carbon footprint?

A popular strategy deployed by many water bottlers to meet sustainability initiatives has been to significantly lightweight their PET containers. However, a recent study has found that while these bottles might meet consumer expectations for convenience and price, they may not minimize the carbon footprint.

Although PET resin suppliers have benefited greatly from the growth of single-serve water bottles, significant research has not been focused on the performance impact and the validation of sustainability assumptions. With industry knowledge and experience being limited in this area, plastic packaging supplier Plastic Technologies, Inc. (PTI) sought to provide brand owners with additional information to facilitate the decision-making process.

Says PTI, since the early 2000s, the weight of a 0.5-L (16.9-oz) water bottle has been reduced in half, possibly pushing acceptance limits for most consumers. Technological enhancements have enabled cost reduction and have contributed to positive environmental impact. Many assume that lighter weight only has positive benefits, but PTI’s research shows that is not always the case.

The study found a wide variation in performance, weight, and recyclability in the bottles it examined. All the packages were commercially-produced for consumers and procured from retail store shelves in the U.S., Europe, and India.

Further, it discovered that lighter weight, and design and label choices have an impact on post-consumer recovery. The decisions made during the design phase not only have to meet physical performance requirements, but also should not negatively impact current recycling systems. While weight reduction results in a lower carbon footprint, it was found that ultra-lightweight bottles can negatively impact the effectiveness of post-consumer package waste sorting and recycling systems.

The study showed that many of the samples did not factor in generally accepted recyclability guidelines during the design process. In some scenarios, the PET package design had strong shelf presence and met the functional requirements. However, the bottle color, label, glue, or ink components had a significant impact on package recyclability.

The study offers extensive data on package weights, wall thickness, pressurization, volumes, optical quality, color, haze, and recycling performance of various commercially-available PET water bottles.