Minimizing Plastic Use in Bottled Water: Quantifying Material Use and Design-Driven Reduction Strategies

The consumption of single-use plastic water bottles has surged over the past two decades, yet guidance on improving bottle design remains limited. To address this gap, we investigated how packaging design, bottle size, bottle components, and polymer composition influence the plastic footprint of bottled water, using carbon content as a proxy. Fifteen bottled water brands, ranging from 0.24 L to 9.5 L, were purchased from U.S. retail stores. Large-capacity bottles—particularly the 4 L size—had the lowest carbon content per unit volume, averaging 13.45 ± 0.84 g/L. In contrast, largely due to differences in packaging design and body wall thickness, the embedded carbon content of small-capacity bottles showed substantial variability. The carbon content of a 0.5L bottle varied from an average of 9.48 to 30.99 g/L. Bulky caps and full-body wrappers also significantly increased carbon. Optimizing packaging weight in widely used 0.5 L bottles—from 51.66 to 15.64 g/L—could yield an estimated annual polymer savings of 0.68 million tons. Most bottles analyzed were made of mixed polymers; for instance, 0.5 L bottles typically consisted of 9.68−31.14 g PET/L, 1.19−4.16 g PE/L, 0.29−1.35 g PP/L, 0.40−1.89 g PVC/L, and 0.03−0.08 g PS/L. These findings highlight the potential need for mono-material packaging and standardized design guidelines, emphasizing reduction in polymer content as a practical strategy to lower the footprint of bottled water across its supply chain.