Degradable, biodegradable, compostable – which should you use?

Degradable, biodegradable, compostable - which should you use?

Do you get confused standing in front of the bin liners at the supermarket?  There are so many different options and some say compostable, others say biodegradable, some just say green or environmentally friendly!  But what do these all actually mean and which should you use?

Let’s begin with explaining the terms degradable, biodegradable and compostable.


Degradable bags are made from plastic (generally polyethylene), which is created from fossil fuels.   Other ingredients are added to the plastic to help it break down and disintegrate over time, but keep in mind this means that it is simply breaking down into smaller pieces of plastic.   It never disappears completely.


Biodegradable bags are still made from plastic but with micro-organisms that help the bag breakdown.  Whilst the bag may break down more quickly, it still breaks down into tiny pieces of plastic that may not ever dissolve completely.  Really,  the term biodegradable means nothing because everything is biodegradable eventually. In the USA, ‘biodegradable’ can only appear on a product if that product is shown to breakdown into elements nature within five years (legislation forbids the use of ‘bio’ if it doesn’t meet these standards’). In Australia, we don’t require any proof, so companies are allowed to use the term ‘bio’ without regulation.  This makes it confusing for the consumer, as many think this means that the product is made from plant matter.


Compostable bags are made from plant based materials and breakdown during the composting process and leave no toxic materials.  A certified compostable product will have the leaf symbol on it.  It may also say certified to Australian Standard AS4736.


What about the bags that say ‘green and degradable’ or ‘naturally degradable’.

This is what we call “green-washing”, which is a misleading claim about the environmental benefits of a product, service, technology or company practice.  Essentially, it makes a product or service company appear to be more environmentally friendly.  The bags that say green or naturally degradable typically will have an additive which makes them break down faster into smaller fragments of microplastics, so they aren’t really green at all.


So which bag do you buy?

For most of us growing up, you used a plastic shopping bag as a bin liner.  But then when the plastic bag ban came into effect, you no longer had these bags (probably hanging in one of those long fabric bag holders behind the pantry or laundry door) to use.  So you started buying plastic bin liners to take their place.  Now, virtually all South Australian councils supply organics and recycling bins or you might have a home compost or chooks, so there is no need to send food waste to landfill.

Compostable bags can be used in your kitchen caddy to capture your food scraps which can go into your organics bin*.  These are the ONLY bags that can go into your green organics bin.  You can also use newspaper to line your kitchen caddy, or no liner at all.

If you are capturing all of your food scraps for composting, along with paper towel and tissues, and you are recycling paper, cardboard, glass, hard plastics and metals,  it means that your waste bin should have very little in it (especially no wet or messy contents).  So do you actually need a bin liner at all?  Whilst you now know the difference between degradable, biodegradable and compostable,  ask yourself the question next time you are at the supermarket.

Tell us your thoughts in the comments below.



*Please check with yourcouncil to make sure that food scraps can go in your organics bin in your local area.  

Posted in Behaviour change, Community, Composting, Family, Plastic, South Australia

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One comment on “Degradable, biodegradable, compostable – which should you use?
  1. Corrien Mon-Kau says:

    I use newspapers. The composting facility in my city does not accept Bio Bags ( what I used before ).

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