What's Not Compostable At Home: 20+ Things To Avoid!

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Composting is confusing. From choosing the best compost bin to finding compost drop-off locations in your state, composting your household waste can feel like an uphill battle. What’s more, not everything is compostable! In a nutshell (no pun intended), there are things you can compost and things you can’t compost, and knowing which is which can leave you scratching your head.

But good news, my friends! Today, we are going to try and make composting a little less bewildering; let’s talk about what not to put in the compost bin.

What is composting?

Composting is the last "R" in the 5 R’s of Zero Waste, also known as rot.

Traditional composting is when microorganisms within the soil use nitrogen, carbon, and water to recompose organic material within the soil layer. This process releases nitrogen, phosphorus, and potassium, providing you with nutrient-rich soil.

Vermicomposting is a little different. With vermicomposting, you are feeding the worms (no, I am not kidding)! And what do worms eat? They munch on organic waste materials and give out excreta that are rich in nitrates and minerals.

In both cases, organic matter is decomposed and broken down into decomposed nutrient-rich organic fertilizers known as humus or 'black gold'.

We should stop here and distinguish the difference between ‘compostable’ versus. ‘biodegradable’. Biodegradable is different from composting; composting requires the presence of worms or microorganisms and oxygen, while biodegradable refers to any material that can be broken down into its original composition. Unlike composting, this process is anaerobic, meaning it can occur with little to no oxygen present. For example, a plastic bag will eventually biodegrade, but it is not compostable.

What can you compost?

When thinking about things you can compost, we can break it down further by understanding the difference between green and brown matter. Green matter is nitrogen-rich and is usually made up of wet materials like plant leaves. Brown matter is carbon-rich and is typically made up of dry material like leaves or wood. While you can compost both, you are striving for a 2:1 ratio of green to brown matter in your compost bin.

Benefits of composting

Beyond healthy soil and happy plants, there are many other benefits of composting:

Composting helps to divert the amount of organic waste being sent to landfills: According to the Environmental Protection Agency (EPA), food scraps contribute to about 30% of all materials sent to landfills. This waste produces methane (a potent greenhouse gas) as it breaks down and contributes to climate change.
Composting saves you money: You will no longer need to buy fertilizer from the store!
Composting helps with soil drainage: By boosting soil moisture; you won't have to water your garden as often.
Composting helps to balance the pH levels in soil: Plants don’t like soil that is too alkaline or acidic, adding green and brown matter to your compost bin can improve this balance.
Composting offers employment and investment opportunities in a growing green industry: On a per-ton basis, composting often offers more jobs than landfills and incinerators!

It’s affordable and accessible: You can buy compost bins that are smaller and can easily integrate into an apartment or condo.

What's not compostable

When composting, think of the compost bin as a little ecosystem. Not everything is compostable, and if you introduce inorganic or organic material that doesn’t belong, you could upset the balance of the ecosystem. Worst case scenario, you disrupt the biodiversity levels in your garden (or wherever your compost ends up) and attract unwanted scavengers like rats, birds, and raccoons in the process.

To add to the problem, some companies advertise products as 'clean', 'organic', or 'ethical' – leading us to believe we can compost the item. These companies are using keywords to greenwash their products and contribute to compost contamination.

Let’s take a look at the things you can’t compost.

Brown Matter from the kitchen:

Teabags contain microplastics and are often not biodegradable (even if the label says otherwise - watch out for greenwashing with this one)!
Stickers: Those pesky stickers on our fruits and veggies are one of the largest contributors to compost contamination. Try and remember to double-check and remove the sticker before composting your food scraps.
Brown and paper bags: While some brown and paper bags are safe to compost, many have a waxy or film lining that should not be added to your compost bin. Aluminum foil and wax paper should also not be composted.

Green Matter from the kitchen:

Organic food waste: We generally think all food waste is compostable, this isn’t true! Foods like citrus peels, garlic, and onions will offset the pH balance of your compost bin and kill your worms. While meat, seafood, and dairy waste are compostable, they will cause a stink in your compost bin and might attract unwanted pests! Luckily, there are second uses for this kind of kitchen waste (like bone broth). If you do compost clean animal bones, grind them down first so they take less time to break down.
Animal excrement: animal waste (especially if the animal is sick) might contain parasites and pathogens that will pass on viruses and can spread to people. Cat litter also cannot be composted.
Oils: Oils, lard, and animal fat won’t break down in your compost bin. This includes salad dressing, bacon grease, or butter.
Processed foods: Processed foods (especially foods with high sugar content) can also disrupt the balance of your compost bin.

Brown Matter from the bathroom & laundry room:

Plastic: Unless your plastic bag or container is a compostable version, do not compost this one. Instead, reuse your old plastic bags and containers to collect rainwater or as replanting pots for your garden. Alternatively, buy plastic free storage containers.
Feminine hygiene products: Sanitary napkins and other women’s personal care products should only be composted unless they are made of 100% cotton (the plastic applicators also cannot be composted).
Diapers: human excrement, like animal waste, should not be composted. Additionally, most diapers are made of harmful chemicals and plastics (instead of composting your diapers, you should try using eco-friendly diapers).
Dryer lint: Lint from the dryer is riddled with microfibers and synthetic textiles from our clothes breaking apart during the wash cycle and can infiltrate the natural environment. The same goes for dust and fuzz from the vacuum cleaner!
Leather: While genuine leather is an animal product, leather takes a VERY long time to break down.

Brown Matter from the garden:

Wood/sawdust: Sawdust and wood from home construction projects are often treated with harmful chemicals that could kill your composting microorganisms. Also, remember to break down large tree branches so they compost faster.
Coal ash: Wood ash is fine to compost, but coal ash releases harmful amounts of sulfur and iron while breaking down.

Green Matter from the garden:

Plants: Hold on, hear me out! Not all plants are compostable. Plants that have been treated with pesticides and herbicides (like lawn trimmings), invasive/toxic plants (like Oleander), or plants that carry infestation or diseases do not belong in your compost bin.

Brown Matter from around the home:

Teabags: Most tea bags are made of plastic and will break down into microplastics. When composting used tea leaves, remember to take them out of the teabag!
Paper and cardboard: This one is tricky. While some paper and cardboard can be composted, treated glossy or colored paper (like magazine pages, receipts, or photos) and coated cardboard (like juice boxes and milk cartons) cannot be composted. Paper that has been written on (with pen ink or markers) can also spread heavy metals and toxins.
Dead animals: Like animal excrement, dead animals might spread bacteria or viruses which can be passed on when you spread your compost.
Cigarette butts: Cigarettes and cigars contain toxic chemicals that you will want to steer clear from adding to your compost bin.

A final word on what's not compostable at home

We hope you now have a better idea of what not to put in the compost bin. At the end of the day, composting is a great option if you have a garden, or you just want to reduce your food waste. In doing so, you will be saving money, contributing to healthier soil, and doing your part to slow climate change.

If composting isn’t for you, there are other ways you can reduce your food waste and take that next step towards a zero-waste lifestyle! Have you ever tried cooking with your food scraps? We have tons of other sources for inspiration here at The Eco Hub!

And make sure you check out all of our composting guides!

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