War on Waste: Do you know how many times you need to use your green bags?

Which type of bag should you use to take your groceries home if you're trying to have as little an impact as possible on the environment?

Plastic bags are banned in South Australia, Tasmania, the ACT and NT.

The answer might seem obvious: a robust and durable bag that can be re-used over and over again.

"If you're able to do that over a long time frame, then you're going to have an environmental advantage," said Associate Professor Karli Verghese from the School of Architecture and Design at RMIT.

But the key words there are "long time frame". Because you might be surprised by the number of times you have to use these bags before they become more environmentally friendly.

Read Michael Collett’s story on ABC News - “War on Waste: Do you know how many times you need to use your green bags?”