Are Compostable Bags Really Compostable? What You Need to Know

Quick Answer

Compostable bags are only truly compostable under the right conditions. Many require industrial composting facilities, not your backyard bin. Always check for certification labels and follow the disposal instructions to ensure they break down as intended.

You've seen the labels: 'compostable,' 'biodegradable,' 'eco-friendly.' But when you toss that bag into your home compost pile, does it actually break down? The short answer is: it depends. Many compostable bags are designed for industrial facilities, which maintain higher temperatures and controlled conditions that your backyard pile simply can't match.

This article separates fact from fiction. We'll explain the difference between compostable and biodegradable, what certifications to look for, and how to dispose of your compostable bags correctly—so you can make choices that truly benefit the planet.

Compostable vs. Biodegradable: What's the Difference?

The terms 'compostable' and 'biodegradable' are often used interchangeably, but they mean very different things. A biodegradable product can break down naturally over time, but there's no guarantee of how long it takes or what it leaves behind. Compostable products, on the other hand, are held to stricter standards: they must break down into non-toxic, nutrient-rich compost within a specific timeframe under the right conditions.

When you see a bag labeled 'compostable,' it usually falls into one of two categories: home compostable or industrially compostable. Home compostable bags are designed to break down in a backyard compost bin, while industrially compostable bags require the higher heat and controlled environment of a commercial facility. Most compostable bags you'll find are the industrial kind, which is why they may not decompose in your home pile.

• Check the label for 'home compostable' vs. 'industrially compostable' before buying.

What Does 'Compostable Bag Certification' Mean?

Certifications are your best guide to knowing if a bag will truly compost. Look for logos from recognized organizations like BPI (Biodegradable Products Institute) or TÜV Austria. These certifications verify that a product meets specific standards for compostability, such as ASTM D6400 for industrial composting or EN 13432 for packaging.

A certified compostable bag has been tested to break down within a certain period, usually 90 to 180 days, in a commercial facility. However, certification doesn't guarantee it will compost in your backyard. For home composting, look for the 'home compostable' certification, which is a separate and more stringent standard.

• If a bag doesn't have a certification logo, treat it as not compostable.

PLA Compostable Bags: The Catch

PLA (polylactic acid) is a common material in compostable bags and food packaging. It's made from renewable resources like corn starch or sugarcane. While PLA is technically compostable, it requires industrial composting conditions—temperatures above 140°F (60°C) and specific humidity levels. In a home compost pile, PLA bags can take years to break down, if they break down at all.

This is a crucial point for eco-conscious shoppers: a PLA bag labeled 'compostable' is often not suitable for home composting. If you don't have access to an industrial facility, that bag might end up in the landfill anyway, where it will behave like regular plastic. Always check the label and your local composting options.

• PLA bags are industrially compostable, not home compostable—unless explicitly stated.

Compostable Bag Myths: Verdicts

• Myth: All compostable bags are home compostable.: Many compostable bags, especially those made from PLA, require industrial composting conditions. Home compost piles often don't reach the necessary temperature or humidity. Check for 'home compostable' certification before adding to your backyard bin.
• Myth: Biodegradable and compostable are the same.: Biodegradable means it will break down eventually, but there's no timeframe or toxicity requirement. Compostable products meet strict standards and break down into non-toxic compost. Choose certified compostable over simply biodegradable.
• Myth: If it says 'compostable,' it's safe to put in any compost.: Industrial compostable bags won't break down properly in home compost. They need the high heat and controlled conditions of a commercial facility. Look for the 'home compostable' label or use a TerraCycle box to recycle them responsibly.

Products That Help You Compost Right

• Biodegradable Plastic - TerraCycle, Recycling Box: This Zero Waste Box accepts all brands of biodegradable or compostable plastic products, such as PLA cups and cutlery, as well as bowls and plates. Does not accept organic substances (e.g., food waste, plants, soil, mulch, etc.), non-biodegradable plastic, paper or wood compostables. If your compostable bags or PLA items can't go in your home bin, this box gives you a responsible way to recycle them through TerraCycle's specialty program.
• Safety Equipment and Protective Gear TerraCycle, Recycling Box: Trash is, sadly, unavoidable. And while curbside recycling can have a huge impact on what heads to our landfills, some types of waste need a specialty recycling center to get the job done. With TerraCycle's Zero Waste Boxes, you can collect your hard-to-recycle materials, and ship it to TerraCycle (for free!) to have them safely and sustainably recycled into something awesome. This box is for non-compostable safety gear, but it shows how TerraCycle helps manage waste that can't be composted—so you can keep more out of landfills.

Compostable bags are a step in the right direction, but they're not a magic solution. To make a real difference, understand what you're buying, check certifications, and dispose of bags according to their specific requirements. When in doubt, use a TerraCycle Zero Waste Box to ensure your compostable items get recycled properly—and keep your home compost pile healthy.