Plastic Vs Stainless Steel Vs Aluminium reusable water bottles

G Magazine

Reusing water bottles is an eco-friendly antidote to single-use disposable plastic bottles, but which of the three main material choices is the greenest option?

Water bottles

The beauty of the reusable water bottles is that they're inherently designed to last for many, many years.

Credit: iStockphoto

- Advertisement -

In our quest for healthy alternatives to sugar-laden soft drinks and juices, bottled water is a hugely popular portable alternative. In 2011 the global market is forecast to be worth more than $90 billion, an increase of 41.8 per cent since 2006. Closer to home, the Australian bottled water market was estimated at $544 million in 2008.

But our thirst for bottled water is leaving a giant-sized eco-footprint. It took a whopping 456,131 barrels of oil to produce the plastic bottles for the 250 million litres of bottled water drunk by Australians in 2006, and according to the NSW Department of Environment and Climate Change, created 60,000 tonnes of greenhouse emissions through production and transportation. What's more, only 36 per cent of drink bottles made from PET (polyethylene terephthalate) are recycled. At best, the rest end up in landfill - at worst, they litter our waterways and oceans.

But don't despair - for those who seek hydration on the go, there are other options. Reusable water bottles made from more durable plastics, stainless steel and aluminium are seen as sustainable alternatives to their single-use cousins as the associated greenhouse gas emissions, water consumption and solid waste are minimised by a longer lifespan. So, of the reusable options, which is the better performer on the eco-ledger?

In the beginning

Long popular with the camping set, aluminium and stainless steel drink bottles are durable and long-lasting. But it's worth considering that, before they line supermarket shelves in bright colours and shiny packaging, their manufacture has a significant impact on the environment.

Pure aluminium is extracted from bauxite (the most significant aluminium ore) and rolled into sheets used in the manufacture of drink bottles. While the raw materials required for its manufacture are plentiful, a huge volume of electricity is also required in the production process. Aluminium production is one of the most energy-intensive industries and in 2008 it generated 14.5 million tonnes of greenhouse gas emissions, according to the Australian Aluminium Council.

Similarly, the process that converts iron ore into stainless steel (where the steel is alloyed with chromium to prevent corrosion and create a shiny finish) is energy intensive. In 2005, BHP Billiton reported the industry created almost 7.5 million tonnes of greenhouse gas emissions.

A 2006 study conducted by Australia's national science agency, CSIRO, found aluminium to have a greater 'cradle to gate' (raw material) environmental impact in terms of energy required and global warming potential than stainless steel.

Simon Lockrey, research fellow in the Sustainable Products and Packaging group at RMIT University's Centre for Design, carried out a life cycle analysis for materials and production of the three alternatives. The analysis found aluminium was the worst performer for water use, stainless steel the worst for solid waste generation and the two metals the worst in terms of global warming impact. Overall, stainless steel was a slightly better performer than aluminium due to lower emissions from the mining of its raw materials and the production process.

So how do the metals stack up against plastic? Drink bottles made from PP (code 5) are thicker, stronger and more durable than their PET (code 1) counterparts and are the material of choice for reusable plastic bottles. But like all plastics, they too are manufactured from a non-renewable resource derived from oil.

According to the Plastic Industry Association, plastic manufacturing uses 2.7 per cent of the total energy consumed in Australia or 8.2 per cent of the energy used in the manufacturing sector, but contributes only 1.4 per cent of the carbon emissions.

Long-life water

The beauty of reusable water bottles is that they're inherently recyclable and designed to last for many, many years. "If a steel or aluminium bottle is retained and reused for a number of years consistently, it is significantly better than a single-use, throw-away drink bottle in environmental terms, even if the PET bottle is recycled," Lockrey says.

He also notes that in kerbside recycling streams, aluminium and stainless steel drink bottles would most likely be picked up and recycled, which would offset some of the impacts of the original manufacture. PP bottles are less likely to be recycled as there isn't a kerbside scheme devoted to just this type of plastic. In fact, 43.1 per cent of PET plastic was recycled in 2009, compared to just 17.4 per cent of PP plastic.

What's more, both metals have achieved high levels of industry recycling. Approximately 75 per cent of the primary aluminium ever produced is still in use, while more than 50 per cent of stainless steel is made from remelted scrap metal.

The verdict

So what's the most environmentally friendly way to rehydrate? It's all over at the beginning of the race, with plastic recording the greenest results in production and manufacture. Lockrey found plastic bottles have around 80 per cent less impact on the environment than the worst performer in all three categories: water use, global warming and solid waste. Although the metals can claim bonus points for recycling, they never recover from the huge investment of energy required in their production processes.

It's also worth noting that plastic bottles are often better suited to our lifestyles. They're lighter and more flexible, which makes them popular as gym companions or desk buddies. And in environmental terms, they're hands down a better option than their single-use, throw-away counterparts.

What about BPA?

Concerned about the health effects of reusable drink bottles? In recent years there has been much debate about bisphenol A (better known as BPA) a chemical in the clear, hard polycarbonate plastic (code 7) used in some water bottles. BPA can act in a similar way to hormones and in some studies on laboratory animals,
this has been linked with effects on the reproductive system. According to consumer advocate Choice, a
major US study has identified a direct link between exposure to low levels of BPA and increased risk of diabetes and heart disease.

Our food regulator, Food Standards Australia New Zealand, says BPA poses no significant health risks at the low levels that migrate from plastic packaging into food and drink, as the BPA is "rapidly inactivated and then excreted in the urine in humans".

PP (code 1) and PET (code 5) plastic do not contain BPA and have no known health hazards. If you are concerned about BPA, a number of brands now make 'BPA-free' plastic reusable bottles.