Does a Compost Bin Need Drainage?

If you’ve seen a compost bin, you’ve probably noticed that there are holes in it. Without fully understanding the composting process, it may not be clear whether these holes are necessary and what they’re for. So, are these holes necessary, and do compost bins need drainage?

A compost bin does need drainage. Drainage usually comes in the form of holes in the compost bin allowing oxygen inside while also releasing excess moisture from the bin. It’s essential for compost bins to release excess moisture to prevent waterlogging.

The rest of this article will talk more about compost bin drainage and why it’s important. 

Why Does a Compost Bin Need Drainage?

A compost bin needs drainage because the composting process requires water, which means there can be excess water buildup. Excess water in the compost bin can become waterlogged, killing important organisms. 

Depending on what you use for composting, you may not see how much of the composting process happens. In fact, you may not know just how much water is necessary for the composting process to be successful. So, let’s talk about it. 

Water is one of the most important parts of composting. In fact, if your compost pile is too dry, then you risk a much longer composting process. Your composting pile should be about 40-60% water. This allows the microorganisms to thrive and complete the composting process quickly. 

This percentage can sound like a lot, but it can make more sense when you consider how much water our natural materials consist of. The water found in composting isn’t just surface water sitting like a lake or a marsh. Rather the water in composting mixes with the materials allowing them to break down. 

So, the composting process doesn’t involve materials sitting in a bunch of water and dissolving. Instead, there needs to be a reasonable amount of water present to prevent the materials from drying out and keep the microorganisms alive. This is where the drainage comes in. 

When it comes to composting, balance is key. And water is no exception to the rule of balance required to maintain good composting conditions and reasonably timely results. This is why you need a drainage system for composting. Too much water can harm the overall compost, while too little can ensure it takes too long and harmful microorganisms. 

If you have ever felt a compost pile, then you know it should feel damp without dripping excess water. To maintain this balance, your compost pile needs to drain. This is why manufacturers create compost bins the way that they do. If you want to know more about the design of compost bins, check out my other article: Do Compost Bins Have a Base on Them?

How Do I Know If My Compost Is Not Properly Draining?

If your compost pile is not properly draining, you’ll notice a foul odor indicating too much water. If your compost pile is draining too much, you’ll notice that the materials feel dry and aren’t composting at a normal rate. 

Now that we know how important draining is for the composting process, let’s talk about how to recognize that it isn’t working properly. First, it’s important to remember that too much draining and too little draining both can become an issue. I’ll discuss both in the following sections. 

Compost Pile Is Not Draining Enough

A foul odor is a sure sign of too much water in your compost pile. The composting process may not smell great, especially if you add certain materials to the mix. But, if you notice that your compost pile smells unbearably foul, then there’s clearly another issue. 

Too much water in the compost pile means that there’s less oxygen. Without enough oxygen, the pile will begin to form a rancid smell. Trust me, you’ll know the difference between this smell and the natural, sometimes musty smell of composting. 

If you want to try to catch an issue of excess water before it makes your compost pile smell, you can always test it yourself. Sure, moisture meters are available if you want to closely monitor the amount of water in your pile, but that’s not completely necessary unless you’re working with many large compost piles at a time, like a manufacturer. 

Alternatively, you can forego the test for one of your own. This simple test can help you figure out pretty quickly if there’s too much water in your compost pile. 

Simply grab a handful from your compost pile and squeeze it. When you first grab the compost pile, water shouldn’t drip from it while holding it in your hand. If it does, there’s too much water in the compost. 

The perfect results for this test are like holding a sponge. While holding it, the pile shouldn’t drip, but you should be able to squeeze a few drops of water from it like a sponge. If a couple of drops of water drip from the pile as you squeeze, then there’s plenty of water. If not, or only a tiny bit drips, then you may need more water in your compost pile to ensure it’s thriving. 

Compost Pile Is Draining Too Much

If your compost pile is draining too much, there’ll be signs that it’s too dry. First, the decomposition process slows down drastically if insufficient water is present. So, if your pile isn’t fitting the typical composting timeline, then you may have an issue with a lack of water. 

This may be difficult to determine for some people as composting different materials can take a different amount of time. So, unless you’re very familiar with the timing of your compost, then you may need to consider other options to tell if it’s draining out too much water and drying out the pile. 

One way you can tell if the pile is too dry is to feel it. Your compost pile should not feel like a dry pile of leaves. Rather, it should feel like damp dirt. If you can feel that the materials are dry, then more water is necessary. 

If you do the feel test to determine the dryness of the pile, make sure you pull from the outer layer of the compost pile. The center of the compost pile is more likely to have moisture, but the outer layer of the pile will give you a more honest feel of how much water is present. 

Remember, the key to composting is that everything breaks down, not just the materials in the center. So, if the outer layer of materials are dry, that means they aren’t decomposing at the same rate as the materials in the center. To avoid this, make sure the entire pile is wet, and ensure that you mix the pile regularly to avoid this. 

How Do I Ensure My Compost Pile Properly Drains?

You can ensure your compost pile properly drains by providing holes for draining and mixing the contents of your pile regularly. Proper mixing will ensure that the excess moisture in certain spots gets spread to other areas that need it. 

For proper drainage, you can make holes on the sides and bottom of the bin if you need to do it yourself. However, most compost bins have drainage systems already in place. 

Beyond ensuring there are adequate holes that water can easily drain out of, you can also ensure that your pile properly drains by mixing it. Mixing the pile ensures that water and oxygen, which are both vital materials for composting, are spread evenly throughout the compost pile. 

If you still notice that there’s too much water in your compost, consider adding more holes for water drainage, as the water may not be working its way to the holes. This can happen if the holes are too far apart or too thin. Composting is not something you’ll master right away. So, don’t be afraid to change your process or bin if needed. 

Final Thoughts

Overall, compost bins rely heavily on drainage to ensure that excess water can escape from the pile. Without it, water will sit in the compost pile, causing it to smell awful and kill important microorganisms that are vital to the composting process. 

Ensure you use the sponge test to see whether your pile has too much or too little water in it and adjust accordingly. Like all other aspects of composting, figuring out the right water level can be challenging. So, keep a close eye on your pile.

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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