Coffee grounds are a great addition to a compost bin, but have you ever wondered if it’s safe to compost coffee filters?

There’s quite a bit of debate out there about whether coffee filters are safe to use in a compost bin and how they can change the health of the organic materials.

Getting to the truth of the matter is no easy task. This article will explain the science behind whether coffee filters are appropriate to add to a compost bin.

Are Coffee Filters Compostable?

Paper coffee filters biodegrade quickly, particularly when added to an active compost bin. But, are they safe?

There has been a tremendous amount of debate about the safety of composting white paper coffee filters. Much of the issue stems from concerns in the 1980s about the use of chlorine-based bleach to strip paper of its natural brown color.

Do Used Filters and Coffee Grounds Change the pH?

Coffee filters and grounds will not drastically increase the acidity in your compost bin. Neutral pH is described at 7.0 on the scale. A pH reading below 7 is acidic, while a reading above is alkaline. Your compost should have a pH between 5.5 and 8 to be safe for gardening use.

You measure the pH with a pH meter. They can be purchased online for less than $10, while more accurate devices may run over $100. Litmus paper is also useful for measuring pH and is an affordable testing solution.

Fresh ground coffee is highly acidic. A freshly brewed cup of coffee has a pH reading of between 4.85 and 5.10. When hot water is passed through the grounds, a significant amount of the acids are rinsed away, and it is these acids that give coffee its unique flavors. Used coffee grounds have a nearly neutral pH reading typically between 6.5 and 6.7.

The pH reading of the coffee filter will also be close to a neutral reading. Due to the nature of filters, the pH will be slightly more acidic than the grounds as the paper will absorb a small amount of acid.

Are White Paper Filters Safe?

In 1987, the Environmental Protection Agency (EPA) began investigating whether levels of the chemical compound dioxin commonly found in white paper products posed a health risk. The New York Times reported at the time the findings were inconclusive, but likely a low-risk to consumers. The EPA began investigating paper mills due to the findings of high levels of dioxins in fish downstream from the paper plants.

In 1990, the EPA announced increasing regulations to eliminate the use of dioxins in the creation of white paper products in the United States. Today, dioxins are no longer in use by paper mills to bleach paper products. Paper manufacturers today use several different processes that are considered to be safer. Most commonly today, companies use a chlorine gas process to remove the color from paper pulp that doesn’t produce dioxins.

The same process used to make coffee filters is also used to make other white paper products, like toilet paper, napkins, and printer paper. Given the tremendous number of consumers in contact with these products, the EPA has strict regulations in place to ensure safety.

Any chance of introducing harmful chemicals to your compost bin by adding used white paper filters is practically impossible. In other words, if the coffee filter was bad for your compost bin, it’d be worse for your cup of coffee.

Can White Paper Filters go in an Organic Compost Bin?

Strictly speaking, the process used to remove the color from wood pulp that results in a white paper introduces a number of chemicals that are considered to be inorganic, such as hydrogen peroxide and elements like oxygen that are neither organic nor inorganic.

While white paper filters have been shown to be safe for use in compost bins, they should be avoided if keeping your bin 100 percent organic is a goal. It’s also best to avoid using coffee grounds made in white paper filters in organic compost bins, as minuscule trace amounts of inorganics may be retained in the grounds.

Are Brown Paper Coffee Filters Compostable?

If you are worried that a white paper coffee filter may upset your compost bin’s balance, an easy option is brown filters. These filters are not bleached, and as such does not contain any of the potentially harmful chemicals. Brown paper filters compost perfectly, but they do not make the same cup of coffee.

Brown paper filters can alter the flavor of the coffee you drink. The reason coffee filters are typically white is to avoid producing “off” flavors. The whitening process removes lignins.

Essentially, these compounds are the “glue” that holds wood products together and gives them the brown color. When you make a cup of coffee through a brown paper filter, some of the lignins will rinse off into the coffee and can produce a paper-like flavor that is off-putting.

Can You Make a Decent Cup of Coffee with a Compostable Brown Filter?

The trick to getting past the lignin flavoring common with brown paper filters is to rinse the filter is clean, hot water. Simply place the empty filter in the basket, then run hot water slowly through making sure to rinse the entire surface from top to bottom. Low-cost filters may need to be rinsed more than once to remove enough of the lignin to prevent off-flavors.

In general, a brown paper coffee filter is considered to be better for the environment since it does not require the extensive process white paper products do. Runoff from paper mills producing white paper filters continues to be one of the leading causes of environmental pollution in the United States.

Switching to brown paper filters may mean a few extra steps, but it’s also a step toward saving the planet.

What’s the Difference Between Biodegradable Filters and Regular Ones?

You may have noticed on your coffee filter aisle, there are packages marketed as biodegradable or compostable filters. These are typically brown paper filters that are made without the use of inorganic compounds. In reality, these filters are not different from other brown paper filters.

Generally, any brown paper coffee filter is considered compostable, and all paper coffee filters, regardless of color, are biodegradable. Exceptions exist: cone filters often use inorganic and potentially non-degradable glue that should be avoided.

Using Coffee Filters and Grounds in Compost

The reason coffee grounds make an excellent addition to a compost bin is because of the high levels of nitrogen present. Nitrogen is one of the three essential building blocks for plant life, and coffee grounds provide an easy and efficient means of increasing nitrogen.

Knowing how many coffee grounds to add to your compost might take a little practice. Generally, it is accepted that between five and twenty percent of your compost can be composed of coffee grounds and filters. Over thirty percent is considered to be unhealthy for the compost bin.

If too much coffee is added, the nitrogen levels will increase causing a rise in temperature. Temperatures over 160 degrees F will begin to kill beneficial microbial bacteria. At temperatures above 180 degrees, the compost pile begins to sterilize. You can reduce the temperature of the compost bin when there are too many coffee grounds by adding carbon in the form of straw, dry grass, and shredded paper.

Coffee filters may help to regulate the nitrogen levels in your compost bin. As paper products such as coffee filters break down they will increase the levels of oxygen and also aid in reducing odors. To speed up the decomposition of paper coffee filters, it’s a good idea to cut or shred them into smaller pieces.

Other Ways to Use Coffee and Filters in Your Garden

Not only are coffee grounds and filters beneficial for plant growth, but there are also other uses you can take advantage of that will help your plants. Coffee grounds can be spread directly on the soil to a depth of about one-half-inch. The grounds slowly add nitrogen to the soil while also preventing slugs and snails from climbing your plants. The caffeine that remains on the grounds is repulsive to slugs and snails.

Used coffee filters are also effective at slowing the growth of weeds around small plants. Simply layer used filters coffee ground-side down around the plants. This will stifle weed growth while allowing moisture to pass through and it will also add fertilizer in the form of nitrogen to the plant.

Alternatives to Coffee Filters

If you are concerned about the environmental impact of the production of white paper products and don’t want the hassle of rinsing brown paper filters, there are some easy options you might consider. One of the best ways to eliminate the waste and hassle of coffee filters is to use a French Press coffee maker.

This design uses a stainless steel mesh screen to press the coffee, eliminating the waste and preserving the grounds in a convenient manner for use in your compost bin.

Many companies today also market reusable metal or nylon coffee filters that will eliminate paper waste and help reduce damage to the environment through the processing of paper pulp.

Conclusion

Coffee filters and grounds are an excellent way to add nitrogen to your compost bin. All paper coffee filters are biodegradable, and it’s safe to use them in your compost bin.

White paper coffee filters are treated with a variety of inorganic compounds that are considered safe for consumer use by the EPA and have not been shown to cause issues in composting.

Brown paper coffee filters are unbleached, therefore less damaging to the environment, but should be rinsed before use to remove unwanted flavors.

Paper filters sold as biodegradable or compostable are likely the same as unlabeled filters but should have higher quality control standards.

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