Since the introduction of 'green bags' to Australian supermarkets in 2002 – and Tim Minchin's 2005 hit 'canvas bags', where the Aussie comedian got the things stuck in everyone's heads – reusable bags have become part of our daily existence. A 2010 CHOICE online reader survey found 62% of respondents use green bags or other reusable bags as their main shopping bag.

These days, there are plenty of sustainable options available to shoppers looking to minimise their environmental impact. The tricky part is, once you look past the presentation, not all of them are as green as they first appear to be. We looked into the issue to find the best sustainable bag option for shoppers and for the environment.

Which bag is best for the environment?

Peter Allan (no, not that one), Principal Consultant at Hyder Consulting, authored numerous studies for the government on the impact of plastic bags, including reports advising which system would be kindest to the environment. This research involved a lifecycle assessment of bag options, including energy and water use, materials consumption, litter and marine impacts across the life of a bag. The analysis found that:

  • Overall, a reusable bag is a better option for the environment than bags with between one and three typical uses. "Given the popularity of the green bags, we needed to test whether reusable was better for the environment and this was comprehensively proven – but only so long as you use it repeatedly over a long period," says Allan. 
  • A green bag has to be used more than 23 times before it becomes a better option than single-use bags.
  • Of the range of reusable bag types tested, the most environmentally-friendly option was the 100% recycled content PET reusable bag, closely followed by the reusable green bag.
  • Calico bags aren't recommended, because of the amount of water used to make them.

Which is the best single-use bag?

On days when you've forgotten to bring your reusable shopping bag and you just can't face buying yet another one to add to your collection, you'll probably end up with a single-use plastic bag. If you buy bin liners, you're also buying single-use plastic bags. Of these, recycled high-density polyethylene (HDPE) bags come out best for their low environmental impact, with paper and biodegradable starch bags at the bottom of the list. 

"Both biodegradable and paper bags use more energy and materials than thin plastic bags to make," says Allan. "And there is little advantage in biodegradable and degradable bags, because most bags end up in landfill where there is no benefit to breaking down – they just create more methane and a less stable landfill site."

Know your bags

Biodegradable: These bags are made from plastic that meets the Australian Standard for biodegradability, and breaks down or composts into carbon dioxide, methane, biomass and water. They're generally made of corn starch or other plant material.

Degradable: Petroleum-based plastic is used to make these bags. They break down into small pieces when exposed to oxygen or sunlight.

HDPE (high-density polyethylene): This is a lightweight plastic that the vast majority of single-use plastic bags are made from.

LDPE (low-density polyethylene): Thicker plastic like this is often used to make customised boutique bags for higher-end shops.

Ban the bag

Although there's no nationwide ban on plastic bags in Australia, many other countries have introduced measures to reduce the use of lightweight plastic bags.

  • Bangladesh was the first country to ban polyethylene bags in early 2002.
  • Ireland was the first country to use a nation-wide levy to discourage plastic bag use in 2002. Within a week plastic bag use decreased from an estimated 328 to 21 bags per capita.
  • China is the largest country that's banned plastic bags. The ban saved the country an estimated 1.6 million tonnes of oil in the year following its introduction in 2008.
  • In November 2013, the European Commission adopted a proposal that requires its 28 Member States to reduce their use of lightweight plastic carrier bags, using whatever measures they like, including charges, national reduction targets or a total ban.

Aussie states go it alone

In Australia, some states have taken it upon themselves to reduce the use of plastic bags. The South Australian government led the way in May 2009, banning the use of single-use plastic bags. Retailers are only allowed to offer biodegradable plastic bags, paper bags and heavy-duty reusable bags, either free or for a charge. Produce and meat barrier bags – as well as bin liners – are exempt from the ban.

The Northern Territory, ACT and Tasmanian Governments followed suit, but the Victorian, Western Australian, Queensland and New South Wales' Governments haven't, despite apparent support from shoppers for a ban on lightweight plastic bags.

Community and retailer responses

Some communities have taken the initiative and banned lightweight plastic bags in their towns. Across Australia, many festivals, events, farmers' markets and entertainment precincts have gone plastic bag-free with community support too.

But the story about retailers is mixed so far:

  • In 2003, Bunnings introduced a 10c charge per plastic bag, which resulted in a 99% reduction in bag usage over five years. In 2008, it removed plastic bags from its outlets altogether, with reusable bags and cardboard boxes becoming popular replacements.
  • IKEA removed plastic bags in 2008.
  • Australia Post stopped offering plastic bags in 2009.
  • Supermarket chain Aldi has only ever offered reusable heavy-duty plastic and green bags available for its customers to buy since opening in Australia in 2001.

But Target backed down in October 2013 and reintroduced free plastic bags after phasing them out in 2009.

And neither Woolworths nor Coles has yet introduced a ban or levy on bags. Though interestingly, all supermarket chains in SA have complied with the ban on HDPE single-use bags without a hitch.