Do Compostable Bags Break Down in Landfills?


Compostable bags are designed (in theory, at least) to help the user leave the smallest possible footprint on the environment. While these bags are evidently useful for composting, you may wonder how eco-friendly they are outside a compost bin. 

Compostable bags do break down in landfills, but that does not necessarily mean you should send them there. The problem with sending compostable bags to landfills is that landfills foster anaerobic conditions, which are not ideal for compostable bags. 

Let’s talk more about compostable bags and the risk of sending them to landfills in more detail below. I will also touch on a possible compostable bag alternative (recyclable trash bags), and its benefits and drawbacks. 

Why You Should Avoid Sending Compostable Bags to a Landfill

It’s easy to assume that compostable bags work much better with landfills than regular trash bags do. However, there is a major drawback to sending compostable bags to landfills — namely, the anaerobic conditions landfills foster.

If you compost regularly, you’re probably aware of the difference between aerobic and anaerobic composting. If not (or if you are but you need a little refresher), here’s a quick recap.

Essentially, aerobic composting introduces oxygen to the composting process, allowing microorganisms that require oxygen to survive long enough to facilitate the processing of composting materials. 

On the other hand, anaerobic composting does not make use of oxygen in the composting pile. Instead, the process produces methane gas, which is characterized by a strong, unpleasant odor. 

Methane’s foul odor isn’t the only reason not to dispose of compostable bags in landfills. According to a report from the United Nations Environment Programme, methane is one of the biggest contributors to global warming to date. The report also cites data by the United States National Oceanic and Atmospheric Administration, which shows that methane production shot up in 2020 even as carbon dioxide emissions went down within the same time period. 

While aerobic and anaerobic composting are both effective, anaerobic composting takes much longer to complete than its aerobic counterpart due to the lack of oxygen, creating minimal heat. 

Landfills tend to be full of waste and dry materials, minimizing the amount of oxygen present there. That means if you put a compostable bag there, it will not receive the necessary conditions to compost within a reasonable amount of time.

What Conditions Do Compostable Bags Need To Break Down?

Composting requires the right amount of materials in the right environment to work properly. Since landfills don’t provide the environment to allow compostable bags to break down, let’s talk about what they do need. I’ve already talked about the need for oxygen, so let’s cover the other factors that compostable bags need to break down. 

Compostable Bags Need the Right Temperature

First, compostable bags need the right temperature for an extended period to compost. Specifically, they need about 90 days to break down, and within that time, the surrounding temperatures need to be at least 113°F (45°C) or above. 

Compostable Bags Need Adequate Drainage

Your compost pile should be able to drain during the composting process so that each material can break down properly. That means compostable bags cannot compost if they’re left sitting in too much water for too long. 

While most landfills have a drainage system, there are sections that may not drain as well as others. This can lead to issues with flooding and prevent compostable bags from breaking down as soon as they should. 

If you want to know more about why proper drainage is an important part of composting, check out my article: Does a Compost Bin Need Drainage. In that article, I break down why draining your compost pile is so important and the negative effects that too much water in a pile can have on the composting process. 

How Do You Dispose of Compostable Bags?

If you can’t send compostable bags to landfills without harming the environment in some way, how do you throw them away once you’re done with them? After all, they’re apparently capable of staying intact for as much as 2 years and 3 months after being buried (though they’re certainly no longer able to carry several pounds or kilos worth of groceries by then).

Unfortunately, the best way to dispose of compostable bags is to take them straight to a dedicated waste processing facility. Since (as previously mentioned) they require specific conditions to break down, and there’s no way to dispose of them at home without harming the environment in some way, you have to leave the job to the professionals. 

For example, if you live in the US, you can use the Environmental Protection Agency’s (EPA) RCRAInfo Web database to search for waste management facilities near you. The search results should show you information such as the type of waste they process, their physical location, and other pertinent information.

If you live outside the United States, check if your government has a similar database in your country. If not, you can always contact the appropriate local government office for information. They should be more than happy to assist you in your efforts to help the environment — or at the very least, keep your local area looking nice and clean.  

Benefits of Recyclable Trash Bags Over Compostable Bags

As I’ve shown above, it can be difficult to dispose of compostable bags unless you’re able to maintain specific conditions. In that case, it may be worth considering alternatives such as recyclable trash bags. 

Here are a few reasons you may want to use recyclable trash bags over compostable bags.

  • Recyclable trash bags can help reduce plastic pollution. Since they’re made of mostly recycled materials, you can rest assured you’re not significantly contributing to the increasing amount of plastics that are wreaking havoc on the oceans and Mother Nature in general. However, that’s not to say recyclable trash bags are 100% environment-friendly (more on this later). 
  • Recyclable trash bags are more durable. If you’re a regular user of compostable bags, chances are you’ve encountered the annoying problem of it getting holes even before you use them. In contrast, recyclable trash bags don’t have that problem (or not as often, at least).
  • Recyclable trash bags are more flexible. Compostable bags can’t exactly accommodate throwaway pizza boxes and the like. On the other hand, you can fit such waste in recyclable trash bags without too much trouble due to the latter’s ability to stretch. 
  • Recyclable trash bags are more affordable. Compostable bags are significantly more expensive than recycled plastic bags, and they have fewer benefits to boot. Even if you can afford to use compostable bags on a regular basis, you (and the environment) may actually be better off using recyclable trash bags instead. 

(One) Drawback of Recyclable Trash Bags

Although recyclable trash bags have significant advantages over compostable trash bags, they have one significant disadvantage — namely, that they’re not 100% recycled. This means that if you dispose of them, they can still harm the environment. Also, if you’re buying bags labeled as “recyclable,” you need to check the components list to ensure that all of them are actually recyclable. 

Recyclable vs. Compostable Bags: Which Is Better?

All of the above said, whether recyclable trash bags or compostable bags are better for you depends on what you need.

If you’re looking for a dedicated bag for composting, compostable bags are a good choice. Just make sure you buy only as much as you need. Not only are these bags relatively expensive, but they’re also difficult to dispose of unless you can create specific conditions for their disposal.

If you’re looking for a relatively affordable and (slightly) more eco-friendly option, recyclable trash bags may fit the bill. They also last longer than compostable bags. However, you should also be aware that they’re not necessarily 100% environmentally friendly. 

Final Thoughts

Compostable bags do not break down easily in a landfill because landfills do not meet the aerobic composting requirements of these bags. If you want to eliminate your use of plastic altogether, a compostable bag can still help, but you should be aware that it requires certain conditions to break down properly. Also, you may want to consider using recyclable trash bags instead.

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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