Are Coffee Filters Compostable? What You Need to Know

Are coffee filters compostable? Most avid gardeners try to compost as much as possible to reduce waste, but can coffee filters go in the compost? This post will cover all aspects of composting coffee filters. Including how long it takes for coffee grinds and filters to decompose, and how to compost them successfully.

Gardeners are always looking for ways to reduce waste and save money. Composting can help with both of these goals. Still, many gardeners worry about whether it is safe to compost coffee filters. Are coffee filters compostable?

The good news is that most coffee filters are made from paper and will decompose perfectly well in a compost pile. However, there are some things you should know before adding them to your pile.

To make sure the process goes smoothly, here’s how you can safely compost coffee filters at home!

Can You Compost Coffee Filters?

The answer is a resounding yes, but ONLY if the filters are made from paper. Before tossing them into your compost, check the box to see if they have a coating or are made of a material that will not break down.

Most coffee filters are paper and will break down in time. Paper is considered brown material, which is rich in carbon. Brown materials are necessary for healthy carbon-nitrogen balances when it comes to compost.

What if they are bleached?

This posts contains affiliate links. This means we earn a commission from sales made via product links in this post. Read our full affiliate disclosure.

Like many paper products, coffee filters are often treated with bleach and other chemicals. Is this something we must worry about?

In a nutshell, not really. Before 1990, elemental chlorine was the primary chemical used to bleach paper. This form of chlorine binds to the cells in the paper products, forming toxic chemicals. The toxins move up through the food chain and become increasingly concentrated. They can cause cancer and other health problems.

The use of elemental chlorine has been phased out in North America. Elemental chlorine-free (ECF) bleaching significantly reduces the production of toxins but does not eliminate them entirely. Click here for more information. These chemicals are only present in tiny amounts, so they will not be an issue for most compost piles.

The bottom line is that if you’re trying to keep your compost completely organic, you’ll want to opt for unbleached filters; otherwise, don’t worry about it.

What about the coffee grounds?

The Oregon State University Extension has studied the properties of coffee grounds. Here is what they found.

The nitrogen content of coffee grounds is about 2% by volume, so they are an excellent nitrogen source. Even though they are brown, they are a good source of nitrogen-rich green material. Which you need to add to your compost. For those that are interested, coffee grinds have a 20-to-1 ratio of carbon to nitrogen.
Do we have to worry about the coffee acidifying our compost pile? Not at all. Since the acid in coffee is water-soluble, it ends up in your coffee mug, not your grounds. Tested the ph of coffee grounds, they were found to have a pH between 6.5 and 6.8 (neutral).
Like most organic materials, coffee grounds can improve the structure of the soil. It can increase water retention and nutrient retention in sandy soils while improving drainage and aeration in clay and silt soils.
Coffee grounds are also reported to repel slugs and snails in the garden. It should be noted that the evidence is anecdotal.

But you know what else? Scientists at The City College of New York found that used coffee grounds can absorb hydrogen sulfide gas. It is this gas that can make your compost smell terrible.

My point is this; coffee grounds are compostable and rich in nitrogen. It only makes sense to compost the coffee grounds along with the coffee filters. And just think, a coffee filter containing coffee grounds provides the perfect brown/green balance for your compost.

How Long Do Coffee Filters Take to Decompose?

Paper takes a longer time to decompose than kitchen food scraps. This is because it has tough fibers that are not quickly broken down by the microbes. The paper needs about 12-15 weeks in a composter that provides optimal conditions for the microbes.
Composting is influenced by climate conditions, particularly temperature, wind, and rainfall. There is not a lot you can do to stop the arrival of winter (if only). However, larger compost piles can stay relatively warm in the middle. Still, you can expect decomposition to stop once you get too icy conditions.

Nevertheless, given time, paper coffee filters do break down into the beautiful rich compost we gardeners know and love.

The following section will provide more details about providing optimal conditions.

How to Compost Coffee Filters

Providing optimal conditions is very important when composting. Here are a few tips to help you get the best results

Compost the Coffee Grounds as Well

Organisms that decompose organic matter need both carbo and nitrogen. Nitrogen plays a crucial role in cell structure, and carbon provides energy. Composting anything with high levels of carbon can cause an imbalance.

Paper is often high in carbon and low in nitrogen. This can slow down how quickly the paper breaks down and causes composting process to take longer. If you want the paper to break down faster, mix it with “green compost” with higher nitrogen content, such as the grounds.

Tear them up

Tearing paper products helps increase the speed at which they are likely to break down. The more surface area they have, the easier it is for bacteria to get in and make them decompose. Tear them into pieces that are less than 2 inches in any dimension.

Watch the temperature

The optimal temperature for the composting process is between 135 and 160 degrees Fahrenheit. This allows microbes to multiply and break down organic material quickly.

Watch the Moisture Content

Compost organisms require water to survive. When the pile dries out, the microbes go dormant or die, and all composting activity stops. The ideal moisture content of a compost pile should be 40-60%. It should feel as moist as a sponge that has been wrung out.

Watch your airflow

The organisms involved in the composting process are aerobic. They need to have an adequate supply of oxygen to be able to decompose the organic matter efficiently.

When you put materials in a pile for composting, the pile should be loosely stacked so there are many air spaces to allow for airflow. It doesn’t matter how high or how wide your pile is, but the height is significant. If the pile is too high, it might get compressed by its own weight, making it harder to turn and break down.

Regularly turning the compost is another way of aerating garden compost. A tumbling composter can be helpful here. We find the coffee filters in our tumbling composter break down a lot faster than anything in our more traditional piles. This is the model we use.

You will know if your compost is not getting enough airflow because it starts to smell terrible. It can also become slimy.

How to add the coffee filter to your compost

You want your coffee grounds to mix into the surrounding “brown” material when you add them to a composter. So, shake them out over the top of the pile. Then tear up the coffee filter and dump it on top. You should be good to go.

Do you see mold in your compost? Read this post to see why. We’ll also tell you when to be worried.

A Few FAQ’s

Are coffee filters bad for the environment?

No, for the most part. If the coffee filters are made of paper, they are biodegradable, meaning they decompose over time. There are some concerns about the use of bleached coffee filters, but the risk is very small.

Are coffee filters green or brown compost?

They are brown compost. Coffee filters are a paper product, and so they are high in carbon which means they are low in nitrogen. The coffee grounds, on the other hand, are green compost despite their color. They are high in nitrogen, and so they are considered “green.”

Are brown paper coffee filters compostable?

Brown coffee filters are usually made from unbleached paper and are biodegradable. Almost all paper coffee filters are generally compostable and biodegradable. If you prefer to use brown unbleached paper filters, you can rest assured that they will compost nicely.

Some coffee drinkers complain that unbleached filters leave a papery taste. You can deal with this by placing the coffee filter in your percolator and pouring hot boiling water over the entire surface. Then make your coffee as you usually do.

Are bamboo coffee filters compostable?

Some consumers are turning to bamboo coffee filters as a more “environmentally friendly” source of paper. This is because bamboo grows faster than most trees used for pulp. Bamboo is a kind of grass and, as such, will break down in the compost just like regular paper filters.

Final Thoughts

We hope that this article has helped answer the question, “Are coffee filters compostable?” We’ve learned that they are safe for our gardens but may need a little bit more time before they’re fully decomposed. We’ve covered all aspects of composting coffee filters, including how long it takes for them to rot. We hope our tips for best practices have also been helpful! Please consider sharing this post with other gardeners who may be interested in our findings.