Mission Compostable

Reusable shopping bags, LED lightbulbs, stainless steel straws – it seems that environmentally friendly options are continually on the rise.

When it comes to compostable bags and packaging however, they might not be the solution you think they are.

Are they environmentally friendly or are they just a load of rubbish?

Chris Purchas, Tonkin + Taylor’s Sector Director for Waste and Chair of WasteMINZ Organic Material Sector Group says that it’s not so much the packaging itself that’s the problem, but the contents inside it that contaminate compost.

“There are some products that should be compostable, for example, small hard to remove food-related items that contaminate compost such as fruit stickers, tea and coffee bags, asparagus ties, and banana tape ”, says Chris.

More and more non-food related products are taking a compostable packaging approach, which can prove to be problematic.

“Packaging for janitorial products, cleaners, shampoos or items such as nappies and sanitary products should not be made out of compostable materials because they devalue compost through potential contamination which can impact on organic certification for compost products and that is an important part of the market for quality compost.”

So if compostable packaging isn’t the solution, what steps can we take?

Kate Boylan, Sustainability Consultant and leader of T+T’s internal Kākāriki (Green) Team, says we need to empower consumers to invest in reusable products that they can use continually and eventually recycle, “Sadly our efforts to switch from single-use plastics to single-use compostables will not fix the worldwide waste crisis. We need to address buying behaviours and encourage consumers to avoid single-use products to begin with”.

Kate’s Composting Tips

Compostable bags and bin liners

Compostable bags only really make sense when they hold other compostable materials, such as food waste that’s destined for composting.

  • In other words, don’t buy compostable bags to line your rubbish bin because they will break down relatively slowly in a low oxygen/anaerobic environment, like a landfill
  • Instead ensure you are splitting your waste effectively (into compost, recyclables and landfill), while leaving the rest of your rubbish reasonably dry. Line your rubbish bins with recycled newspaper – or don’t use a liner at all

Compostable coffee cups

Compostable cups are pretty pointless unless they are properly disposed of at a commercial compost facility.

  • Instead invest in a reusable coffee cup, like a ‘keep-cup’ or sign up to your favourite café’s cup lending programme
  • In most cases, reusable is better than compostable

Compostable food packaging

Food manufacturers are increasingly making the switch to compostable packaging as plastic alternatives improve and become more accessible and affordable. However, most packaging is not yet able to break down in a home-compost system, and require commercial composting which most NZ households do not have access to.

  •          Compostable packaging in a home-compost system will have a pretty high risk of incomplete degradation, leaving behind plastic fragments, and contaminating your compost
  •          Meat contaminated packaging could attract rodents into your home compost
  •          Instead try reducing your meat intake, or shopping at a local butcher and bulk food stores with your own containers


For more information on the relationship between compostable plastics and the environment, you can read the Parliamentary Commissioner for the Environment’s report here.