Do You Really Need Compostable Bags for Your Food ...

If you save food scraps for composting, lining your kitchen collection bin with a bag labeled as compostable or biodegradable may seem like a great way to keep it clean and transport all those veggie peels and coffee grinds to your compost heap or municipal dropoff point. However, whether or not you actually need to buy those liners depends on several factors—and in fact, many experts say it’s better to forgo liners altogether or just reuse paper bags instead.

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Here's what you need to know about compost bin liners, why they may do more harm than good even if they’re compostable, and how you can keep your kitchen tidy without them.

What are compostable bags or bin liners?

Compostable bags may look and feel similar to plastic produce bags made from petroleum, but they’re manufactured out of plant-based materials, such as vegetable starches, wood pulp, lactic acid, or soy proteins. These materials are designed to be consumed by microorganisms that help them decompose into the soil-like organic substance we know as compost.

The problem is that not all composting systems create the right environment for these bags to fully break down. Typically, only municipal or commercial composting facilities—not home composting setups—generate enough heat, moisture, and airflow to allow for full decomposition. But these facilities can also differ in their capacities, so even if your food scraps get collected for off-site composting, compostable bags may still be prohibited.

Can I put compostable bags in with my food waste?

It depends. Just as every town seems to have its own set of rules about what kind of recycling it accepts, one composting system may differ from another in its ability to take compostable bags.

The most important thing you can do is confirm with your municipal collection, compost drop-off, or private composting service what kinds of materials are and aren’t allowed and then abide by that.

If you are allowed to use compostable bags, your best bet is to look for ones with a logo from the Biodegradable Products Institute, a not-for-profit organization that issues a compostability certification widely considered the gold standard in the US. (You can also check here to see if an item is BPI certified.) The certification relies in part on ASTM International compostability standards to determine whether an item will break down “quickly, completely and safely, when composted in well-run municipal and commercial facilities.” It also prohibits the addition of per- and polyfluorinated substances (PFAS), which are sometimes used in packaging and can persist in the environment for a very long time.

Can I put compostable bags in my home compost heap?

You probably don’t want to, since they likely won’t decompose well. At-home composting systems, including tumblers, in-ground composters, and worm towers, typically don’t generate enough heat to fully break the bags down. “We have experimented with trying to compost these bags in backyard tumblers and did not have much success; they composted somewhat, but definitely not fully,” Michelle Bradley, co-founder of Java’s Compost, a private composting service in New Jersey, said in an email interview.

Can I compost so-called biodegradable plastic bags?

No, you can’t. A bag (or another disposable item, like plastic cutlery) that’s labeled biodegradable is not necessarily also compostable. In fact, BPI executive director Rhodes Yepsen said in an email interview that biodegradable is a word that’s “too vague to be meaningful” as a marketing term on its own without additional context. A manufacturer can call an item biodegradable without specifying that the degradation process could take centuries or require a specific environment to thoroughly degrade. The term also doesn’t necessarily mean that the item breaks down into nontoxic components, either; it just means that, sooner or later, it breaks down into something else.

“It’s not a real thing,” at least not in terms of waste management, said New York City Department of Sanitation commissioner Jessica Tisch in a phone interview. “If a product can’t be composted, it’s going to a landfill. And if it’s going to a landfill, the biodegradable stuff in a landfill sits there for decades or centuries.”

How can I keep my kitchen scrap bin clean?

Some cities suggest residents use brown paper bags or newspaper as liners for their food-scrap containers instead of buying so-called compostable bags. But as always, if you’re participating in an off-site composting program, it’s best to confirm if paper bags are accepted. For at-home composting, brown paper bags are a great addition to your pile, since paper goods can improve the nutritional balance of compost.

Stashing food scraps in your freezer is another way to keep things tidy and odor free. Tisch (who opts for this method at home) noted that if you store your compost in the freezer you can forgo a countertop bin altogether; instead, you can use something like an old plastic takeout container, which you can wash between uses.

If you opt for a countertop container, one with a built-in charcoal filter helps reduce odor. (The Oggi Countertop Compost Pail comes with a filter and is a staff favorite.) And, of course, if you take out the bin often and rinse it out after each use, smells shouldn’t build up in the first place.

If you’re looking for more recommendations about what to do with those scraps after you’ve collected them, check out our staff’s favorite compost bins.

This article was edited by Katie Okamoto and Christine Cyr Clisset.

Sources

1. Michelle Bradley, co-founder of Java’s Compost, email interview, September 13, 2022

2. Rhodes Yepsen, executive director at Biodegradable Products Institute, email interview, September 19, 2022

3. Jessica Tisch, commissioner of the New York City Department of Sanitation, phone interview, September 29, 2022

Bin with compost items and suggestions on what to do with paper and compostable bags, Union Square ... [+] Farmer's Market, New York City. (Photo by: Joan Slatkin/UCG/Universal Images Group via Getty Images)

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According to research conducted by packaging platform Sourceful, only 3% of compostable packaging in the U.K. ends up in a proper composting facility.

Instead, it claimed a lack of composting infrastructure means 54% goes to landfill and the remaining 43% gets incinerated.

Sourceful’s CEO and co-founder, Wing Chan, said the practical reality of compostables “does not reflect the narrative used to market them”.

“We recommend avoiding and looking to switch out where possible in your supply chain,” added Chan.

Dr. Tarun Anumol, from Agilent Technologies, said plastic bags are commonly made from the polymer polyethylene, which depending on the conditions can take up to 1,000 years to fully break down in the soil.

And when they do start to disintegrate, Anumol added they can frequently break down into micro-plastics, which research shows can contaminate the soil, be absorbed into crops or pollute nearby water streams.

Once in the water supply or food chain, they can then be ingested by humans and enter the bloodstream.

In addition, he said microplastics can also attach to other pollutants and even increase the toxicity of other substances in the soil, like chromium and other organic pollutants.

In terms of compostable bags, he said many of them take between 10 and 60 days to degrade in the soil, depending on favorable environment conditions.

He said in some instances, home composting does not necessarily provide the right environmental conditions for decomposition, so the bags may “stick around for a lot longer” but still not as long as traditional plastics.

Anumol said it was important that the right disposal systems are in place to manage compostable bags, but he added this is really a “teething issue” that will be sorted out over the next few years.

But he said it was still vital that soil is regularly tested and analysed for possible contaminants to ensure safe and fertile soil.

Sarah Paiji Yoo, the CEO and co-founder of the eco-friendly cleaning product firm Blueland said ultimately, she believes compostable bags are still better than virgin plastic bags, because they are not made with petroleum-based plastic.

But she added compostable bags need to be industrially composted to truly effectively degrade.

“Compostable bags that are put in the trash can last in a landfill for tens and hundreds of years since objects in landfills,” she added.

The CEO of plant-based fiber packaging manufacturer Footprint, Troy Swope said he believes we are “not quite there yet” with compostable bioplastics.

“When we started Footprint, we considered bioplastics, but ultimately we found the best solution for the planet was a nature-based solution,” Swope told Forbes.

Swope said they use recycled cardboard, paper and other natural substances, like algae to develop a fiber, which in turn, can be used to create biodegradable packaging.

“We want solutions that nature can digest, so that if it got into a river and into your ocean, it would break down will not harm sea life,” he added.

And Graham Rihn, founder and CEO of the waste management platform RoadRunner Recycling, said it was important to draw a distinction between biodegradable bag liners and compostable liners, which he added are designed for a very specific function.

Ultimately, he said if there is compost service available, then “you should absolutely use compostable products, if at all possible”, because it will leave a far smaller footprint on the environment than the alternative.

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