Int​roduct​​​​ion 

Single-use plastic water bottles can provide convenience, but their use is a controversial topic due to their environmental concerns. In 2021, polyethylene terephthalate (PET) packaging accounted for 44.7% of single-serve beverage packaging in the USⁱ. The following is a review of the environmental impacts throughout the life cycle of a standard 500 mL PET water bottle, primarily energy consumption and greenhouse gas (GHG) emissions.

Material Production 

Fossil fuels, namely crude oil and natural gas are extracted and refined to produce ethylene glycol (EG) and purified terephthalic acid (TPA). EG and TPA are combined to form PET resin. The PET resin is then pelletized to form PET resin pellets to be used in bottle manufacturing.​

Environmental impact estimates: 

Energy consumption: 70 – 83 MJ/kg of PET resin^{ii iii iv} ≈ 1.06 – 2.463 MJ/500mL bottle 

GHG emissions: 2.19 – 2.733 kg CO2-eq/kg of PET resin^{ii iv} ≈ 0.0379 – 0.0625/500mL kg CO2-eq bottle 

Waste produced: 0.091 – 0.141 kg waste/kg of PET resin^{ii​ iv​} ≈ 0.0014 – 0.0042 kg waste/500mL bottle

Bottle Fabrication 

The PET resin pellets are injection molded to form tubes. The tubes are then stretch blow molded to form single-use PET water bottles. 1 kg of PET resin can be used to produce 0.877 kg of finished 500 mL bottles^v or 33.7 – 65.94 bottles, depending on the mass of the bottle (13.3 – 26 g)^{v vi vii}. 

Environmental impact estimates: 

Energy consumption: 8.388 – 20 MJ/kg of bottle^{iii v viii} ≈ 0.1116 – 0.52 MJ/500mL bottle 

GHG ​emissions: 0.034 – 0.046 kg CO2-eq/ 500 mL bottle^v

Bottling Operation 

Water is typically treated and filtered through processes such as reverse osmosis, UV, and ozone treatment. The plastic water bottles are then filled with the treated water and packaged for distribution. 

Environmental impact estimates: 

Energy consumption: 1 x 10^-4 – 0.1617 MJ to treat each L of water^{iii vi} 

                                       ​​​​0.003 – 0.006 MJ/500 mL PET bottle filled^{iii vi} 

GHG emissions: 0.01 kg CO2-eq/L of water treated^vi 

                              2 x 10-4 kg CO2-eq/ 500mL PET bottle filled^vi​​

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​Use 

Single-use plastic water bottles are typically disposed after drinking, as they are not intended for reuse due to health concerns^ix. The potential source of environmental impacts during this phase of the life cycle is chilling the water bottle prior to consumption. 

Environmental impact estimates: 

Energy consumption: 0.2-0.4 MJ/L of water chilled (refrigerated up to 1 week)^{iii vi} 

GHG Emissions: 0.0248 kg CO2-eq/L of water chilled (refrigerated up to 1 week)^vi​

​Disposal 

PET water bottles are typically disposed of in three ways: recycling, incineration, and landfilling. In the United States, an estimated 29.1% of PET bottles produced were recycled in 2018^x. The conventional method of PET bottle recycling is mechanical, in which the recycled bottles are shredded, cleaned, and reprocessed into recycled PET pellets to be used in recycled PET water bottles and other products. Plastic bottles are also incinerated for the purpose of energy recovery. Nevertheless, incineration can produce significant GHG emissions. Most bottles are discarded, typically in landfills, for over 69% of plastic container and packaging waste in 2018^x. However, these water bottles may also find themselves in waterways and pollute the environment. PET plastic bottles take up to 500 years to degrade^xi​ and can be a source of plastic pollution and microplastics in drinking water and the environment^xii. ​

Environmental impact estimates: 

Energy consumption: 0.097 MJ recovered/500 mL bottle incinerated^vii 

                                       0.595 MJ recovered/500 mL bottle recycled^vii​ 

GHG emissions: 0.0211 kg CO2 eq/500 mL bottle incinerated^vii​

                              0.9 x 10-3 kg CO2 eq/500 mL bottle landfilled^vii 

                              0.0114 kg CO2 eq prevented/500 mL bottle recycled^vii​​

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​​Transportation 

Transportation between and within the stages of the water bottle life cycle above can be done by truck, rail, or ship depending on the specific circumstance. The resulting energy consumption and GHG emissions can vary greatly. Transportation can be a major source of environmental impact in the life cycle of a water bottle in cases where there are large distances between material sources, water sources, manufacturing sites, and/or disposal sites^{iii​ vi vii}.​
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^​​i Benyathiar, P., Kumar, P., Carpenter, G., Brace, J., & Mishra, D. K. (2022). Polyethylene Terephthalate (PET) Bottleto-Bottle Recycling for the Beverage Industry: A Review. Polymers, 2366. Retrieved Aug 22, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9231234/​ 

ⁱⁱ Franklin Associates. (2011). Cradle-To-Gate Life Cycle Inventory of Nine Plastic Resins and Four Polyurethane Precursors. American Chemistry Council. Retrieved Aug 22, 2023, from https://www.americanchemistry.com/better-policy-regulation/plastics/resources/cradle-to-gate-life-cycle-inventory-of-nine-plastic-resins-and-four-polyurethane-precursors

ⁱⁱⁱ Gleick, P. H., & Cooley, H. S. (2009). Energy Implications of Bottled Water. Environmental Research Letter. Retrieved Aug 22, 2023, from https://iopscience.iop.org/article/10.1088/1748-9326/4/1/014009​

^iv The Committee of PET Manufacturers in Europe. (2017). Polyethylene Terephthalate (PET) (Bottle Grade). PlasticsEurope. Retrieved Aug 22, 2023, from https://plasticseurope.org/sustainability/circularity/life-cycle-thinking/eco-profiles-set/ 

^v Benavides, P. T., Dunn, J. B., Han, J., Biddy, M., & Markham, J. (2018). Exploring Comparative Energy and Environmental Benefits of Virgin, Recycled, and Bio-Derived PET Bottles. ACS Sustainable Chemistry & Engineering, 9725-9733. Retrieved Aug 22, 2023, from https://pubs.acs.org/doi/full/10.1021/acssuschemeng.8b00750​ 

^vi Franklin Associates. (2009). Life Cycle Assessment of Drinking Water Systems: Bottle Water, Tap Water, and Home/Office Delivery Water. State of Oregon Department of Environmental Quality. Retrieved Aug 22, 2023, from https://www.oregon.gov/deq/FilterDocs/wprLCycleAssessDW.pdf 

^vii Gironi, F., & Piemonte, V. (2010). Life cycle assessment of polylactic acid and polyethylene terephthalate bottles for drinking water. Environmental Progress & Sustainable Energy, 459-468. Retrieved Aug 22, 2023, from https://aiche.onlinelibrary.wiley.com/doi/full/10.1002/ep.10490 

^viii Papong, S., Malakul, P., Trungkavashirakun, R., Wenunun, P., Chom-in, T., Nithitanakul, M., & Sarobol, E. (2014). Comparative assessment of the environmental profile of PLA and PET drinking water bottles from a life cycle perspective. Journal of Cleaner Production, 539-550. Retrieved Aug 22, 2023, from https://www.sciencedirect.com/science/article/pii/S0959652613006331 

^ix Bottled Water: Questions and Answers. (2022, Oct 03). Retrieved Aug 22, 2023, from Minnesota Department of Health: https://www.health.state.mn.us/communities/environment/wate​​r/factsheet/bottledwater.html 

^x Containers and Packaging: Product-Specific Data. (2022, Dec 03). Retrieved Aug 22, 2023, from United States Environmental Protection Agency: https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycling/containers-and-packaging-product-specific

^xi Orset, C., Barret, N., & Lemaire, A. (2017). How consumers of plastic water bottles are responding to environmental policies? Waste Management, 13-27. Retrieved Aug 22, 2023, from https://pubmed.ncbi.nlm.nih.gov/28117128/ 

xii Microplastics in drinking-water. (2019). World Health Organization. Retrieved Aug 22, 2023, from https://iris.who.int/bitstream/handle/10665/326499/9789241516198-eng.pdf?sequence=5​