Plastic bags have long been a staple of everyday life in Australia, from the bin liner in your kitchen to the carry bag at the checkout, the courier satchel on your doorstep, and the heavy-duty liner on a factory floor. They are practical, lightweight, and remarkably versatile. But growing awareness of plastic pollution has pushed both consumers and businesses to ask a reasonable question: is there a better way?
Biodegradable plastic bags have emerged as one answer to that question. Over the past two decades, the technology behind them has moved well beyond novelty status. Today, biodegradable bags are used across households, commercial kitchens, retail operations, and industrial sites throughout Australia. They are not a perfect solution, and it is important to understand exactly what they can and cannot do. But for the right applications, they represent a genuine step forward.
At Plastpack, we have been manufacturing bags for Australian businesses and households since 1928. In that time, we have watched the industry evolve considerably, and biodegradable materials are one of the most significant developments of recent decades. This guide covers what biodegradable plastic bags actually are, how they are made, where they perform well, and what you need to know before making the switch.
What Does “Biodegradable” Actually Mean?
The word biodegradable is used so frequently in product marketing that it has lost much of its precision. At its most basic, biodegradable means that a material is capable of being broken down by living organisms, typically bacteria and fungi, into simpler natural compounds such as water, carbon dioxide, and organic matter.
The problem is that almost everything is technically biodegradable given enough time. A standard polyethylene bag will eventually degrade, but it may take several hundred years to do so. When manufacturers label a bag as biodegradable, they are implying that breakdown happens within a more meaningful timeframe, but without certification and defined test conditions, that implication is not always backed by evidence.
This is why the term biodegradable alone is not enough information to make an informed purchase. You need to know what the bag is made from, under what conditions it breaks down, and how long that process takes. The answers vary considerably between products.
How Biodegradable Plastic Bags Are Made
Biodegradable plastic bags are not all made the same way. There are several distinct approaches used in the industry today, each with different materials, performance characteristics, and environmental outcomes.
Oxo-Degradable Bags
Oxo-degradable bags are conventional polyethylene bags with a pro-oxidant additive, typically a metal salt compound, blended into the plastic during manufacturing. This additive causes the plastic to oxidise and fragment more quickly when exposed to heat, UV light, and oxygen.
The result is that the bag breaks down into smaller and smaller pieces of plastic over a shorter period than an untreated polyethylene bag. However, and this is a critical point, those smaller pieces are still plastic. The bag does not biodegrade in a biological sense; it simply fragments. The end product is microplastics distributed in the environment, which poses its own set of ecological concerns.
Oxo-degradable bags have faced significant regulatory scrutiny in recent years. The European Union banned them in 2021. In Australia, they remain available but are increasingly viewed with scepticism by environmental scientists and waste management professionals. If a bag is labelled simply as “degradable” without any certification logo, there is a reasonable chance it is oxo-degradable.
Hydro-Biodegradable (Bio-Based) Bags
Bio-based biodegradable bags are made from plant-derived polymers rather than petroleum. The most common raw materials include corn starch, sugarcane, cassava, and other agricultural crops. These materials are processed into polymers such as PLA (polylactic acid) or blended with other biodegradable co-polymers to create a film suitable for bag manufacturing.
Unlike oxo-degradable bags, bio-based bags are designed to break down through genuine biological processes. When exposed to moisture, heat, and microbial activity in a suitable composting environment, the polymer chains break apart and the material is consumed by microorganisms, leaving behind water, carbon dioxide, and biomass with no persistent plastic residue.
The catch is that most bio-based bags require industrial composting conditions to break down within a practical timeframe. In standard landfill conditions, without adequate heat, moisture, or microbial activity, they may take considerably longer to degrade than their marketing suggests.
Starch-Blend Bags
Starch-blend bags combine thermoplastic starch (typically from potato, corn, or tapioca) with other biodegradable polymers such as PBAT (polybutylene adipate terephthalate). This blend creates a film that is more flexible than pure PLA and can be processed on conventional bag-making equipment.
Starch-blend bags tend to be more moisture-sensitive than standard plastic bags, which can be a limitation in some applications. However, for organics collection and light household waste, they perform well and break down effectively in appropriate composting environments.
Certification: The Detail That Matters Most
If there is one takeaway from this guide, it is this: when buying biodegradable bags, always look for independent certification from a recognised body. The certification tells you far more than the marketing language on the packaging ever will.
In Australia, the relevant standards are:
AS 4736: This standard applies to biodegradable plastics suitable for composting and other microbial treatment. It covers industrial or commercial composting conditions, where temperatures typically exceed 55 degrees Celsius. Products certified to AS 4736 must break down to at least 90% mineralisation within 180 days, leave no harmful residues, and support plant growth in the resulting compost.
AS 5810: This standard covers biodegradable plastics suitable for home composting. The conditions are less controlled than industrial composting, with lower temperatures and variable moisture levels. Products certified to AS 5810 must demonstrate complete breakdown within 12 months under simulated home composting conditions.
The Australasian Bioplastics Association (ABA) administers a certification scheme for both standards and licenses the use of a seedling logo on products that have passed independent testing. This logo is your most reliable indicator that a biodegradable or compostable bag actually performs as claimed.
Other internationally recognised certification marks include those from TUV Austria (the OK Compost range) and the Biodegradable Products Institute (BPI) in North America, which you may encounter on imported products.
Where Biodegradable Bags Genuinely Make a Difference
Understanding where biodegradable bags add real environmental value requires thinking carefully about the entire lifecycle of the bag, from production through to end-of-life. The honest answer is that their benefit depends heavily on how they are used and where they end up.
Organic Waste Diversion
This is where biodegradable bags, and particularly certified compostable bags, have the clearest and most defensible environmental benefit.
Across Australia, councils are steadily expanding food organics and garden organics (FOGO) collection services. These services collect organic waste from households separately and send it to industrial composting facilities rather than landfill. When organic waste goes to compost rather than landfill, it avoids producing methane, a potent greenhouse gas generated when organic matter decomposes anaerobically in landfill conditions.
Using a certified compostable bag as the liner in your kitchen caddy allows you to collect food scraps cleanly and conveniently, then place the whole bag, contents and all, into your organics bin. At the composting facility, both the bag and its contents break down together. This is the application where biodegradable bags most clearly justify the additional cost and any performance trade-offs compared to conventional plastic.
Retail and Light Commercial Use
For retailers, event organisers, and light commercial operators looking to reduce their plastic footprint, certified biodegradable carry bags and bin liners offer a practical alternative to conventional polyethylene. They perform adequately for everyday use, particularly where waste is light and dry, and they signal a genuine commitment to more responsible packaging.
Household Kitchen Bins
For general household kitchen bins, biodegradable bags offer a reasonable compromise for households that want to move away from conventional plastic but are not yet part of a FOGO collection scheme. The bags will perform similarly to standard plastic bags for everyday kitchen waste, though users should be aware that they are more moisture-sensitive and should be stored away from heat and humidity.
Catering and Hospitality
Commercial kitchens and food service operations generate significant volumes of organic waste. Businesses in this sector that have access to commercial composting services, either through a council programme or a private organic waste contractor, can gain meaningful environmental benefits from switching to certified compostable bin liners. The bags allow staff to collect food waste hygienically without needing to separate the bag from the contents before processing.
Honest Limitations: What Biodegradable Bags Cannot Do
Responsible purchasing decisions require understanding the limitations of a product, not just its benefits. Biodegradable bags have several genuine limitations that are worth acknowledging.
They Are Not a Solution for Landfill
The vast majority of rubbish bags in Australia, biodegradable or otherwise, end up in landfill. If a biodegradable bag ends up in a conventional landfill, it is unlikely to break down significantly faster than standard plastic. Modern landfills are engineered containment systems designed to be dry, stable, and low in microbial activity. The conditions that biodegradable polymers need in order to break down quickly, heat, moisture, and active microbial populations, are largely absent.
Choosing a biodegradable bag for your general rubbish bin and sending it to landfill does not deliver the environmental benefit that the marketing might imply. The benefit is realised only when the bag enters an appropriate biological treatment pathway.
Moisture Sensitivity Can Be a Practical Problem
Bio-based and compostable bags are more sensitive to moisture than conventional polyethylene. In a warm, humid environment, or when used to line a bin that collects wet waste over several days, they may soften, become sticky, or develop small holes. For some applications, this is a manageable inconvenience. For others, particularly in industrial or commercial settings where bags must hold heavy or wet loads, it is a meaningful performance limitation.
Shelf Life Is Shorter
Because they are designed to break down, biodegradable bags have a finite shelf life. Stored in warm, humid conditions, some bio-based bags will begin to degrade while still in the box. They should be stored in cool, dry conditions and used within the period recommended by the manufacturer. For businesses that buy in bulk, this is worth factoring into purchasing decisions.
Production Still Has an Environmental Cost
Bio-based polymers are derived from agricultural crops, which require land, water, fertilisers, and energy to grow and process. The manufacturing of biodegradable bags is not without environmental impact. Life cycle assessments of bio-based bags versus conventional plastic bags produce mixed results depending on the methodology used and the end-of-life scenario assumed. Biodegradable bags are not inherently “clean”; they simply have a different environmental profile.
What to Look for When Buying Biodegradable Bags in Australia
With so much variation in quality and so many environmental claims in the marketplace, here is a practical checklist for evaluating biodegradable bags:
Look for the ABA seedling logo. This is your most reliable indicator of genuine certified compostability in Australia. It means the product has been independently tested against AS 4736 or AS 5810.
Check whether the certification is for industrial or home composting. AS 4736 requires industrial composting conditions. AS 5810 is suitable for home composting. The distinction matters depending on how you intend to dispose of the bags.
Be cautious of “degradable” without certification. As discussed, this term often indicates an oxo-degradable product that fragments into microplastics rather than genuinely biodegrading.
Consider the application. A certified compostable bag is the right choice for your kitchen caddy if your council runs a FOGO service. For general rubbish, a high-quality polyethylene bag may be the more honest and practical option.
Check the thickness and load rating. Biodegradable bags, like all bags, come in a range of thicknesses. Match the bag to the application. A lightweight bag used for heavy waste will split regardless of what it is made from.
Buy from a reputable manufacturer. Quality control in bag manufacturing matters. Consistent film thickness, reliable seam strength, and batch-to-batch consistency all affect how a bag performs in practice. Buying from a manufacturer with a track record and an in-house production process reduces the risk of poor-quality products.
Biodegradable Bags and Australian Waste Policy
Australia’s approach to waste and packaging is evolving. The National Packaging Targets, developed through the Australian Packaging Covenant Organisation (APCO), set goals for packaging to be reusable, recyclable, or compostable by 2025 and beyond. Several state and territory governments have also introduced or expanded bans on single-use plastics, including lightweight plastic carry bags.
In this context, biodegradable and compostable bags are playing a growing role in Australia’s waste management landscape. Many councils have updated their kerbside collection guidelines to specify certified compostable liners as the accepted bag type for food organics bins. Retailers and food service operators are increasingly moving to certified compostable carry bags and packaging as part of their environmental commitments.
It is worth noting that biodegradable bags do not automatically satisfy single-use plastics bans. The specific regulations vary by state and territory, and some bans apply to bags below a certain thickness regardless of the material. If you are purchasing bags for commercial use, it pays to check the current regulations in your state before making a decision.
Plastpack and Sustainable Bag Solutions
At Plastpack, we have been manufacturing bags in Australia since 1928. Over nearly a century, we have adapted to significant changes in materials, technology, and market needs. The growing demand for biodegradable and environmentally responsible bag options is one of the more significant shifts we have seen in recent decades.
Our manufacturing facility holds approximately 50 tonnes of film stock at any given time and operates with in-house film extrusion, printing, and bag-forming capability. This means we maintain control over quality at every stage of production and can turn orders around quickly.
We supply garbage bags, bin liners, carry bags, food packaging, industrial bags, and a wide range of other products to customers across Australia, from individual households to large commercial and industrial operations. If you are looking for guidance on choosing the right bag for your application, whether that is conventional polyethylene, a certified biodegradable option, or something else entirely, our team is available to help.
Frequently Asked Questions
Are biodegradable plastic bags actually better for the environment than regular plastic bags?
The answer depends on how and where the bags are used. Certified compostable bags used to collect organic waste that is diverted to an industrial composting facility deliver a clear environmental benefit. They reduce the volume of organic matter going to landfill and avoid the associated methane emissions. However, if a biodegradable bag ends up in a conventional landfill, the environmental benefit is much less clear. Most landfills are not designed to support the biological breakdown that biodegradable materials require, so the bag may persist in landfill for a similar length of time to a conventional plastic bag. The environmental advantage of biodegradable bags is realised primarily through the waste stream they enter, not simply through the material they are made from.
How can I tell if a biodegradable bag is genuinely certified in Australia?
Look for the Australasian Bioplastics Association (ABA) seedling logo on the packaging, along with a reference to Australian Standard AS 4736 (for industrial composting) or AS 5810 (for home composting). These certifications indicate that the product has been independently tested and verified to meet specific breakdown criteria under defined conditions. If a bag carries only a “degradable” or “eco-friendly” label without a recognised certification mark, there is no guarantee that it performs as claimed. Certification is the most reliable way to distinguish genuine biodegradable products from greenwashing.
Can I put certified compostable bags in my home compost bin?
Only if the bags are certified to AS 5810, which is the Australian standard for home composting. Bags certified only to AS 4736 are designed to break down under the higher temperatures of industrial composting facilities and may not break down adequately in a home compost system. If you want to compost bags at home, check the packaging specifically for AS 5810 certification and the ABA seedling logo with a home composting designation. Even with the right certification, breakdown will be faster in a well-maintained, hot compost system than in a cool or slow compost pile.
Why do biodegradable bags sometimes feel different from regular plastic bags?
Bio-based and compostable bags are made from different polymer materials than conventional polyethylene, and the physical properties of those materials differ. Some biodegradable bags feel slightly stiffer, less stretchy, or more paper-like than standard plastic bags. Others, particularly starch-blend bags, may have a faintly earthy or starchy smell. These differences are a natural result of the plant-derived materials used in manufacturing. Performance characteristics such as puncture resistance and moisture tolerance also differ from conventional plastic, which is why matching the bag to the right application is important.
Do biodegradable bags cost more than standard plastic bags?
Yes, in most cases they do. Bio-based polymers are more expensive to produce than petroleum-derived polyethylene, and the manufacturing process for certified biodegradable bags tends to be more complex. The price premium varies depending on the material composition, the volume purchased, and the certification standard the bags meet. For household use, the cost difference per bag is often small in absolute terms. For businesses purchasing in large volumes, it can be more significant. The additional cost is best justified when the bags are being used in an application that genuinely delivers an environmental benefit, such as organic waste collection destined for composting, rather than general rubbish destined for landfill.