Skip to Content

Does Composting Kill Bacteria?

Composting is one of the best ways to recycle and reuse food scraps, dead plants, and other organic materials. However, many piles have every requirement to grow all types of bacteria. Some of us try to remove or prevent bacteria, but is it even possible?

So, does composting kill bacteria? Yes and no. Composting kills bacteria if you allow the temperature to increase over 150°F (65.5°C). However, certain kinds of bacteria are actually beneficial. For this reason, some composters will intentionally lower the temperature to allow good bacteria to thrive.

Throughout this article, you’ll also learn the following information:

  • Different types of good and bad bacteria
  • How compost piles interact with bacteria
  • Should you be worried?
  • How you can remove to prevent bad pathogens
  • Which ingredients promote bacteria
  • Additional tips about composting and bacteria

What Kind of Bacteria Can You Find in Compost Bins?

Most types of bacteria need three things to thrive:

  1. Oxygen
  2. Moisture
  3. A food source

On paper, compost piles provide everything they need to reproduce and consume anything in their way. You can find all sorts of bacteria in your compost pile, but they’re all considered either aerobes or anaerobes.

Aerobes are microorganisms that require oxygen to live. Bacteria that need oxygen found in compost piles will survive without a problem, especially if you properly aerate the soil as often as you should.

On the other hand, anaerobes are a type of microorganism that doesn’t require oxygen as much. In fact, some of them die if they encounter too much oxygen. It’s much harder for this type of bacteria to thrive in a properly maintained compost pile.

Many aerobes, such as Bacillus, release nutrients that are essential to plant life when they excrete after eating. These nutrients include magnesium, nitrogen, and phosphorus; Coincidentally three of the most important parts of composting.

Anaerobes bacteria isn’t nearly as good for composting as aerobic bacteria. They produce chemicals that can prove toxic to plants and soil, making them bad for your compost pile and yard. They also excrete hydrogen sulfide that creates a foul odor throughout the garden.

If your compost bin is loaded with aerobes, you’ll be able to enjoy a healthy decomposition process. After all, microorganisms are a leading cause of compost piles working successfully. They help to break down waste while also leaving behind nutrients. You’ll get the best of both worlds from this good type of bacteria.

Unfortunately, anaerobic bacteria can be hard to avoid if you don’t properly maintain your compost pile. You can introduce more oxygen in the pile, but some of these bacteria are resilient enough to tear through a pile in a matter of weeks. For more information about removing bad bacteria from your compost, refer to the section below.


Salmonella is one of the most tricky types of bacteria in the world. It’s aerobic in nature, but it can switch to an anaerobic form if it needs to adapt to the local environment. This ability to adjust so quickly makes it nearly impossible to kill or remove by aerating a composting pile.

You can introduce salmonella into your compost pile on accident by throwing in raw meat or eggs. Although most eggs don’t have salmonella, there’s a small chance that you could toss one into the bin that does.

Salmonella is notorious for creating gut-wrenching symptoms. Here’s a list of side effects of ingesting salmonella:

  • Fever
  • Diarrhea
  • Vomiting
  • Nausea
  • Chills
  • Headache
  • Stomach ache
  • Abdominal cramps
  • Blood in stools

As you can see, there are a plethora of terrible symptoms that accompany the ingestion of salmonella. By keeping raw or undercooked meat and eggs out of your composting pile, you can avoid salmonella.

Despite all of the unsettling possibilities, you don’t have to worry about anything else bringing salmonella into your compost bin. It’s uncommon in almost anything else, although a few other animals are known to carry it. However, they won’t bring it into your pile unless they die inside of it.

E. Coli

E. Coli is another nasty bacteria that finds its way into compost piles. Much like salmonella, E. Coli can be anaerobic or aerobic depending on whether or not oxygen is present. This trait makes it challenging to rid it from your compost pile without throwing it all out and starting brand-new.

Most of the symptoms that come with having E. coli in your system include bowel cramps and diarrhea. In some instances, patients may experience vomiting or nausea, though they’re not nearly as common as the aforementioned symptoms.

E. Coli is found is human and animal stools, making it easy to avoid. However, if you have a pet or local animals living in the environment who keep going to the bathroom on your compost pile, you could have a problem on your hands.

Contaminated food, especially leafy greens, are the main cause of widespread E. Coli infections. The reason is that farm animals go to the bathroom wherever they walk, making it dangerous if they find their way into the food area.

As long as you can prevent animals from dropping stools in the compost bin, you should be fine. Also, make sure that you stay up to date on local E. Coli outbreaks so you don’t accidentally dispose of a contaminated food source into the pile.

What Other Dangerous Bacteria Are There?

Bacteria thrive in the environment created by most compost piles. They have a food source, adequate moisture, and the perfect temperature. Even if you increase the temperature, there are a few types of bacteria that can survive. They’re known as Thermus bacteria, and they thrive in warm soil and water.

That being said, not all Thermus bacteria are bad. In fact, many of them are vital to the decomposition process of your compost pile. However, if you’re not able to control the temperature naturally, then you might have to fight off a couple of dangerous types of bacteria.


Legionella is a group of pathogenic bacteria that can cause serious illnesses, including the well-known Legionnaire’s Disease. It usually only causes congestion, mild fevers, chills, and other symptoms similar to the flu. However, it can adapt and progress to be fatal in rare circumstances.

It’s an aerobic bacteria, which means that it requires at least 5% oxygen to survive. Unfortunately, your compost pile also needs a lot of bacteria. To make matters worse, plenty of compost ingredients sold in the UK and Australia have Legionella according to the Daily Mail.

Legionella can be killed by increasing the water temperature of your pipes. Although they thrive in moist, hydrated environments, this type of bacteria doesn’t do too well with heat. The presence of Legionella is common, but getting an infection is quite rare.

If you contract Legionnaire’s Disease from Legionella in your compost pile, you either have to heat the pile up or throw it out and restart like new. Letting it sit will only promote growth and reproduction, further increasing your chances of becoming infected.


Actinomyces are not quite as common as Legionella in compost material, but they thrive in moist soil. If you happen to come across Actinomyces, you could contract the rare but very serious Actinomycosis.

The reason that this type of bacteria isn’t as common in compost piles is that it’s anaerobic, which means that oxygen can’t be present. They can actually be completely killed or removed by aerating your compost pile. However, a pile that’s left unchecked can quickly harbor Actinomyces.

You’ll know almost immediately due to the foul rotten egg stench that’s created by their waste. They’ll eat all of the material and break it down into toxic, harmful chemicals that can prevent growth in your garden.

Prevention is always the best way to stop Actinomyces from ever showing up. Since you’re supposed to mix your compost pile regularly, they shouldn’t start growing or consuming the organic waste. The oxygen that’s present will be more than enough to ward them off.

Note: Actinomyces shouldn’t be confused with Actinomycetes, a good bacteria that are found in healthy compost piles. Actinomycetes decompose organic waste and allow your compost to breathe and break down as it should.

Which Composting Ingredients Harbor Bacteria?

It’s been thoroughly established that not all types of bacteria are bad. Without the good kind of bacteria, composting wouldn’t even work in the first place. Bacteria are necessary to break down organic material throughout the planet on a daily basis, which is why they’re included in many compost bags.

If you’re trying to accelerate the process of composting, you might want to try out a compost soil bag. Jobe’s Organic Compost Starter is an excellent product that will help your compost bin to start decomposing regularly.

Although most companies don’t intentionally add bacteria to their composting ingredients, it’s nearly impossible to prevent them from coming along for the ride. Since they’re ever present in soil and moist environments, there’s virtually nothing companies can do to prevent bacteria from infiltrating the compost material.

One of the main types of bacteria that you’ll find in compost ingredients is Actinomycetes. Remember that this is the healthy kind of bacteria, not to be confused with the bad, anaerobic Actinomyces.

Most compost piles are broken down by Actinomycetes at a healthy rate, which is why nobody makes a fuss about their presence. They gradually chow down on your organic waste and excrete all sorts of healthy nutrients. Truthfully, they’re one of the main reasons that your compost pile will create fresh soil for years to come!

If you live in a cold environment, then you might be familiar with psychrophiles. They’re a type of good bacteria that thrives in freezing temperatures. Unlike most other bacteria, psychrophiles don’t need warmth to work. In fact, they decompose compost piles at a quick pace when it’s cold outside.

Whether your organic compost ingredients have warm-weather inhabitants, such as the Thermus bacteria, or cold-weather bacteria, such as Psychrophiles, it’s safe to say that we all rely on the good bacteria for our bins.

The bad news is that many companies don’t have a way to keep Legionella out of their products. When you use sawdust and other dusty products, there’s a chance that you’ll inhale Legionella. It’s considered very rare to deal with the bacteria, but it’s worth mentioning that they’re occasionally found in store-bought products.

The best way to prevent such issues is to create a compost pile with nothing other than your own household waste. Try grass clippings, newspaper, dead leaves, coffee grounds, and uneaten food scraps.

How to Prevent Compost from Getting Bad Bacteria

There’s no denying that all compost piles will eventually have to deal with bad bacteria. After all, you’re creating an environment that they need to live and reproduce. For more information about how you can kill bad bacteria that are already present in your compost, proceed to the next section.

Since the best way to stop a bacterial spread is prevention, let’s review five ways that you can stop them from arriving:

  1. Increase the amount of oxygen in your compost pile. As we’ve covered already, anaerobic bacteria are often the cause of foul odors and toxic soil. Since they can’t be exposed to too much oxygen, all you have to do is aerate your pile regularly to prevent them from growing. Once to three times a week should be more than enough.
  2. Get the proper green to brown ratio in your compost bin. Carbon and nitrogen are both essential, but too much of either of them will start to invite bad bacteria. Follow a 30:1 ratio of brown to green organic materials. This will allow good bacteria to thrive and will prevent bad bacteria from arriving.
  3. Don’t let the temperature dip. When it gets between 50 to 110 degrees Fahrenheit (10 to 43 C), bad bacteria are able to tear through organic material in a short period of time. Since they release toxic chemicals, it creates an even better environment for them to keep eating and growing.
  4. Always monitor what goes into the pile. As mentioned throughout this article, Salmonella and E. Coli can both be introduced to your compost bin by throwing out bad food. Uncooked or raw meat scraps, contaminated leafy greens, and feces can cause these nasty bacteria to grow.
  5. Keep an eye on the companies that you buy organic materials from. Some companies are more prone than others to have Legionella in their compost bags, so watch for news reports and customer reviews to figure out which companies are safer than others.

How to Kill Bad Bacteria in a Compost Pile

Since it’s been mentioned that bad bacteria will inevitably find its way to your compost pile, you need to make sure that you’re ready and prepared to deal with it. If you gather the proper tools and maintain your compost pile as it should be, then you’ll be equipped to stop a spread in its tracks.

Copyright protected content owner: and was initially posted on April 30, 2020.

Here’s a handful of suggestions to kill bad bacteria in a compost pile:

  • According to the Center for Disease Control and Prevention, Legionella can’t live beyond 140 degrees Fahrenheit (60 C). While maintaining a high temperature is definitely going to prevent bad bacteria, you might have to increase it even more to kill off an infestation. 158 degrees F (70 C) is thought to be the perfect temperature.
  • Use a shovel or a rake to lift the bottom ingredients to the top of the pile. This simple motion will bring loads of oxygen to the pile instantly. All of the anaerobic bacteria that lived at the bottom will now be exposed, dying within minutes.
  • Adjust the moisture levels in your compost bin. Some bad bacteria need more water, while others need less. If you know what type is present in your compost material, you can change how much moisture soaks the pile. You’ll end up flooding or drying out the bad bacteria.
  • Use ultraviolet light lamps to kill bad bacteria on the surface of the compost pile. Ultraviolet lights are used to disinfect surfaces, and you can install them around your compost area to use once in a while. They’re relatively affordable and they don’t harm the pile or animals nearby.
  • Remove spoiled ingredients that act as a food source. It’s no secret that anything without a source of food will eventually cease to exist. If you take out rotten meat, old eggs, and other ingredients that serve as a primary food source for dangerous types of bacteria, they’ll die soon enough.

As you can see, there are quite a few different ways to kill off bad bacteria when you’re fixing a compost pile. However, one of the biggest factors is the temperature. Read on to see how you can adjust the temperature range of your compost pile to kill bad bacteria without damaging the composting process.

What Temperature Kills Bad Bacteria for Composting?

Bad bacteria thrive in a wide range of temperatures. You can have one species that lives in 60 degrees Fahrenheit and another that requires at least 90 degrees. The good news is that most types of bacteria can’t survive in boiling hot or freezing cold temperatures.

As mentioned in the preventative and removal sections, Legionella can’t survive anything over 140 F (60 C). If you increase the temperature of your compost pile, you’ll kill most bad bacteria in a few minutes. 158 F (70 C) will be enough to stop the spread and end all presence of Legionella right away.

On the other hand, freezing out bacteria is another option. The problem with freezing a compost pile is that it’s nearly impossible for it to operate correctly. Fortunately, psychrophiles can live and decompose your organic compost pile in super-low temperatures. If your compost has psychrophiles, then you don’t have much to worry about.

Copyright article owner is for this article. This post was first published on April 30, 2020.

The problem is that there’s no real way to know if you have different types of bacteria unless you have the soil tested. If you don’t have psychrophiles in your compost pile and you drop the temperature drastically, you could end up damaging the process beyond repair. Everything will be preserved, which means it won’t break down as you want it to.

Whether you’re overheating bad bacteria or freezing it, the ball is in your court. You can decide the safest course of action for your compost pile. Remember that prevention is always the best way to go about a pile, but it’s not always possible. By following these temperature guidelines, you should be able to maintain a healthy compost bin.

When Should You Worry About Bacteria?

We all know that bad bacteria can cause serious illnesses. Whether you’re avoiding such health concerns or you’re looking after the well-being of your compost pile, it’s crucial that you get rid of bad bacteria as soon as possible. If it’s left to reproduce, you’ll have to get rid of the pile and restart.

Don’t worry, though; It’s very easy to get rid of bad bacteria as you’ve hopefully read above. However, there’s a time to stress if you notice that the symptoms of a bad pile aren’t going away. Look out for these signs to determine if you should take action:

  • If there’s a rotten smell, then there’s a problem. Your compost should smell like fresh earth, almost similar to healthy grass and trees. If you notice that it smells more like a trash can or spoiled food, then there’s a high chance that anaerobic bacteria have found a way inside.
  • If you’re feeling ill every time you deal with your compost pile, it’s another sign for concern. Legionella, salmonella, E. Coli, and all sorts of other bad bacteria can make you feel sick. Symptoms can be mild, but you shouldn’t be getting sick from working on a compost pile.
  • If your compost pile feels slimy, you should start to add moisture and oxygen. Slime is a sign of bad bacteria and not enough moisture. Your compost pile should feel like wet dirt, but not quite muddy. By stirring it around with a rake and spraying it down with a hose, you’ll fix the issue.
  • If your compost material takes too long to break down, then you probably have bad bacteria. They start to eat away at healthy nutrients while also introducing toxic chemicals into the pile. This combination is horrible for your compost, which leaves it looking like a pile of moist dirt.
  • If there aren’t any bugs in your pile, then bad bacteria is probably preventing them from arriving. Bugs, such as ants and worms, are essential for a healthy compost pile. They promote the decomposition process, while also adding good nutrients when they die. It’s a win-win combo that you’ll miss out on if you have bad bacteria in the compost.

Can You Use Chemicals to Kill Bacteria in Your Compost?

Sometimes, it can be tempting to spray chemicals on a compost pile to kill bacteria. Unfortunately, most of these chemicals will end up killing the bugs that help to decompose the organic waste found in the pile. It’s better to avoid spraying anything other than water onto a compost pile.

That being said, what if you have plant life with chemicals already on them? Since they’re a huge part of the process, you can’t cut out half of your pile’s ingredients, right? Let’s examine a scenario:

One of the best ingredients to throw into your compost pile is old, dead plants. Grass, weeds, seeds, sticks, bark, and other plant parts help to accelerate the decomposition process. However, you might be worried about the presence of pesticides and herbicides on these plants.

For example, if you spray a pesticide chemical on a bush to kill pests, but then it dies later from natural causes, can you still put that chemically-treated dead bush into the pile? Yes! Remember that pesticides and herbicides are designed to kill specific bugs and plants. As long as you’re not using the compost to grow more weeds, you’ll be good to go.

To wrap up the answer, you can’t spray chemicals directly on a compost pile because it’ll kill helpful bugs and bacteria. It’ll also kill some types of bad bacteria but at the cost of never being able to use any of the soil from your compost pile.

Final Thoughts

Composting isn’t known to directly kill bacteria. In fact, it can harbor all sorts of good and bad bacteria throughout its lifetime. If you properly maintain the pile, you shouldn’t have to worry too much about the presence of bad bacteria. Remember that the ingredients that go into the pile are going to prevent or invite all sorts of pathogens.

ReadyToDIY is the owner of this article. This post was published on April 30, 2020.

Here’s a quick recap of the post:

  • E. Coli, salmonella, legionella, and actinomyces are some of the most common composting bacteria.
  • Always wear gloves when you’re dealing with compost material.
  • 158 degrees F (70 C) will kill most types of bad bacteria).
  • Thermus bacteria thrive in hot temperatures, while psychrophiles live in freezing temperatures.
  • Don’t spray toxic chemicals on a compost pile.