How Long Do Compostable Cups Take To Decompose?

How Long Do Compostable Cups Take To Decompose

As individuals work to lessen their impact on the global crisis, many are turning to compostable products to avoid disposable plastic products. Plastic cups, for example, are estimated to take about 450 years to decompose. The disposable plastic cups at the ready today will likely be here long after we’re gone. 

So, let’s look at the compostable cups we choose as an alternative. How long do they take to decompose? Are they actually better than plastic? We’re here to explain, so stick around to learn more!

What Are Compostable Cups Made Of?

For the most part, the compostable cups you see at the supermarket are bio-based plastic and consist of renewable plants. The material is usually made up of corn starch, but it can be derived from varying plant-based starches. 

From a chemical standpoint, this material is known as Poly Lactic Acid or PLA. The material closely mimics traditional plastics; side by side, many folks can’t tell the two apart. However, the green band around the bottom of the cup gives a telling indicator. 

Most manufacturers add some sort of marking on the cups to indicate the product is compostable, usually in the form of a green band around the bottom of the cup. However, some manufacturers stamp the cups with a message, often saying something along the lines of, “I am not plastic. I’m *material*.”

Are Compostable Cups Biodegradeable?

“Compostable” and “biodegradable” are commonly confused and used interchangeably. However, while they both apply to how an item breaks down, they aren’t the same thing. Every compostable item is biodegradable, but not all biodegradable items are compostable. 

How so? To understand this, we need to look at each term on its own. 

Compostable

An item labeled as compostable tells you the product is capable of decomposing and returning to its natural elements in a compost environment. These items, like fruits, vegetables, and PLA (compostable cups), consist of natural ingredients. 

So, if you put these items in the right environment, they’ll eventually become compost. Generally, most things take about 90 days or less to compost, although this varies based on the item in question. 

Many people have compost piles at home, where they discard compostable scraps, like eggshells, coffee grounds, fruit and vegetable trimmings, and other food items. Once the scraps fully decompose, they create rich soil full of nutrients. Most folks add the nutrient-rich soil to their gardens and lawns, using it as a soil amendment for better plant growth. 

Biodegradable

Hundreds of products today boast a ‘biodegradable’ label, suggesting that this particular product is safe and good for the environment. However, this can be far from the truth. As we mentioned earlier, compostable products are always biodegradable, but it doesn’t always apply the other way around. 

The reasoning for this is due to how biodegradable items break down. The definition states biodegradable items are capable of being broken down by the action of varying microorganisms (such as bacteria or fungi). 

The primary difference between biodegradable and compostable items is the time frame for decomposition. There’s no precise time limit on how long biodegradable items take to break down entirely. It could be a few weeks, years, or even millenniums. Compared to the 90 days most compostable items decompose, this is a massive difference. 

On top of that, unlike compostable items, biodegradable items don’t always leave behind beneficial leftovers that enrich the soil around them. Instead, some of them can harm the environment as they decompose, expelling harmful oils and gases as they degrade. 

Consider a biodegradable plastic bag. While it is labeled biodegradable, it could take decades to break down entirely. As it decomposes, it releases harmful CO2 emissions into the atmosphere. So although ‘biodegradable’ is often construed as a positive thing, it isn’t always good for our planet as we’ve been led to believe. 

Do Compostable Cups Break Down In Landfills?

Although compostable cups will break down rapidly in the right environment, they don’t break down as quickly as you’d think, especially in a landfill. Let’s say you accidentally send used compostable cups from your backyard cookout to the landfill. 

Once they reach the landfill, the employees at the site bury the trash bags, just like they do with most trash. When these compostable cups are buried, they’re still technically compostable. 

However, instead of breaking down and enriching the surrounding soil within a few months, these cups can take decades to decompose fully. Unfortunately, they could potentially take over a century to completely decompose. 

So, should you recycle the cups instead? Perhaps you accidentally toss the cups into a plastic recycling bin, or maybe you think it’s the better alternative. The problem with this is the composition of the cups – they aren’t plastic, so they contaminate the recycling process.

Plastic recycling processes are designed for recycling exactly that – plastics. So, when you add compostable cups to the process, things get problematic. 

Can I Put Compostable Cups In My Compost Bin?

Compostable cups featuring a PLA lining (the bioplastic made from corn starch) are technically compostable, hence the name. However, don’t let it confuse you, as these cups are unsuitable for home composting. 

For these cups to decompose, they need a specific composting environment, one that the home composting process usually doesn’t offer. So, the best way to dispose of your compostable cups is by sending them to an industrial composting facility to undergo their recycling process. 

Unfortunately, these facilities are few and far between, so it can be tricky to dispose of compostable cups safely. You can check online for composting facilities in your area, although there may not be one close nearby. 

If you toss these cups in your home compost bin, they could take a year or longer to decompose fully. Considering most compost decomposes within 90 days, this is more than outside the typical range. 

What Should I Do With Used Compostable Cups?

While the idea of compostable products is excellent in theory, we need more processing facilities before it’s the ideal choice. These products break down much faster than traditional plastics but still require a special facility for processing. 

They can’t safely go into plastic recycling, as they’ll contaminate the process due to their composition. Even though the green band on the bottom of the cup may seem to indicate the cup is a recyclable plastic product, this isn’t the case. 

Compostable cups shouldn’t go in your home compost bin, either. They could eventually decompose there, but it’ll take months, even years, for the process to complete. This might be your best bet if you don’t have any other options (other than the trash). 

Unfortunately, the next best option (if you don’t have a local composting facility or a compost pile) is the trash. Although the cups will end up in the landfill, they will eventually decompose, even though it could take a century. 

What Should I Use Instead Of Compostable Cups?

Compostable cups are arguable a recycling nightmare. There isn’t a good place to dispose of the products without a nearby industrial composting facility. They’ll take months to years to decompose in a home composting setting since they require additional heat, and they’ll last over a century buried in a landfill. 

So, what should you use instead of compostable cups? As you’d probably imagine, the best option is to use reusable cups. While it isn’t as convenient since you’ll have to wash all those cups, you won’t have to worry about where to dispose of them. 

If you regularly use compostable coffee cups each morning, consider replacing them with silicone, glass, or ceramic coffee cups. These aren’t single-use cups, so you can wash and reuse them indefinitely. If you don’t mind silicone, consider investing in a collapsible cup. They’re easy to carry around since they collapse into a small disc, taking up little space in your bag. When you’re ready, simply pop it up and use it.

Of course, using reusable cups isn’t ideal in all scenarios, so you might use compostable cups or plastic cups every once in a while. There isn’t a catch-all solution that works ideally in every scenario. Maybe, one day in the future, industrial composting facilities will be more widespread, giving us the opportunity to use and dispose of compostable cup waste effectively.