Will Pouring Potting Soil Down a Drain Clog It?

When repotting or watering houseplants, I prefer using the sink. It is less messy and more comfortable than any other surface in my home. Unfortunately, a lot of potting soil collects in the sink, and like me, you have probably attempted to wash it down the drain, a mistake I have vowed never to repeat.

Potting soil cannot go down the drain because it is dense and easily clogs the drains. It can also contain organic amendments like peat moss. Some of these materials are too huge to go through the drain and can decay, leaving your drain with an awful smell while attracting pests.

In this article, I’ll explain why you shouldn’t pour potting soil down the drain, how to avoid it, and what you should do if some potting soil accidentally goes down the drain.

Why Potting Soil Shouldn’t Go Down the Drain

Potting soil might go down the drain in multiple ways, such as when washing your garden gloves, watering your plants, or moving your houseplants from one pot to another. Whether you accidentally wash the potting soil down the drain or not, it will affect your drainage system.

Here’s why you should let potting soil get in your drain:

It Contains Several Materials

Potting soil mix is made up of different materials. The soil in the mixture may smoothly go through the drain, but the other materials, such as rice hulls, peat moss, composted bark, and manure, will not. 

Organic Material Decays Slowly

Organic material in the potting mix takes too long to decay. So, you will likely deal with clogged drains before they break down enough to allow the water to pass through. 

Some Materials Will Cause Backups

Some materials in potting mix do not absorb water readily. For instance, peat moss will likely block the drain and cause a backup.

The Smell May Attract Pests

As the organic matter in potting soil decomposes in the pipes, they will release a foul smell that will attract pests. You will also have to deal with the smell coming through the drains in your house. 

So many awful things will happen if you pour potting soil down the drain, so it’s best to find other ways to get rid of potting soil.

This Is How Potting Materials Clog Pipes

It’s usually best not to put anything but water and soap down the drain, even coffee grains and food matter. Your sink is not designed to withstand heavy and compacted mixtures and is only built for water drainage. 

Therefore, the likelihood of a drain blockage is relatively high if you’ve been throwing unnecessary matter down it for an extended period of time. 

This is because drains are easily blocked, making your life more difficult in the long run. While it’s usually a simple fix to get your drains unclogged, you may find the job much more difficult if they’re blocked up with potting soil. 

Pouring potting soil down a drain is very likely to clog it because when soil absorbs water, it clumps. When this happens, it might take a similar consistency to cement, becoming so compacted that it forms a giant mass that melds itself to the walls of the pipes. 

Additionally, potting soil contains microorganisms that can, if left unchecked for too long, emit a bad smell. Bacteria and fungi will begin to decay inside the drains, which is never a pleasant experience, and it may even draw in rats, something that is never ideal for a homeowner.

Home Remedies for Soil-Clogged Drains

Potting soil can go down the drain accidentally. You may unintentionally open the faucet after repotting your plants, only for the soil to go into your plumbing system. 

You don’t need to panic because there are steps you can take to stop the soil from clogging the drains:

Use a Plunger

Use a plunger to push as much soil as possible out of the drain. If very little potting soil went into the drain, you would have no problem. The pressure from the plunger is enough to force the dirt and other potting material from the drain.

Pour Hot Water Into the Drain

Pouring hot water into the drain might flush out the remaining debris. It can also remove the oils in the system that may cause the potting mix to stick to the side of the pipes and the drain.

Use a Drain Cleaner

If the water in your tub or sink is not moving as fast as it usually does, you should use a drain cleaner to help clear up any blockages.

Try Baking Soda & Vinegar

Mix baking soda with vinegar and pour the mixture down the drain, then let it sit and work on the materials in the system for at least an hour. Flush with hot water.

This video shows how you can unclog your drain using baking soda and vinegar:

Expert Hack: Remove the Soil Mass Using a Drain Snake

At this point, if you’ve poured a lot of potting soil down your drain, and you’ve tried everything listed above, it’s best to remember that, without a professional, you won’t be able to dissolve the contents of the drain by yourself.

Using products such as bleach or vinegar just won’t do the trick in this case. Instead, you’ll need to resort to a more hands-on manner. 

To that end, you don’t want to put anything down your drain unless you’re sure it’s a certified way to fix your problem, as you’ll only end up with a heftier bill at the end of the day. 

Since soil is one of the more frustrating things to remove from your drain, you’ll need something powerful to remove it. One of these options is a drain snake, which may sound terrifying, but it usually does the trick with significant blockages. 

There are a few different types of drain snakes, and depending on your needs, you may need the more powerful option, which is a hand-held drill drain snake. This is a powerful beast guaranteed to remove any amount of potting soil.

To use a drain snake to remove the potting soil from your drain, follow the instructions below:

Remove Part of the Drainpipe

Take off the curved part of the drainpipe closest to the sink. You should be able to pop it off easily by hand, but if you’re having trouble, you can use pliers or a similar sharp utensil to force the edge off the drain. 

Extend the Snake Into the Drain

Push the end of the drain snake outwards and extend it out into the drain. Try to push it downwards since this is likely where the blockage is. 

Twist When You Feel Resistance

Once you feel some kind of obstruction, twist the handle to grab it. After a couple of twists, you shouldn’t be able to twist the handle anymore. 

Pull the Snake Toward You

Very gently, pull the drain snake back out of the drain towards you. If you get a bit of resistance, you can untwist it slightly to see if that will get you more traction. 

Remove It From the Drain

Pull the drain snake out of the drain and watch the contents come out. Since the soil was already compacted, it should come out as a compact mass, but you can always put the snake back in to check if there are any remnants.

Last Resort: Contact a Plumber

Potting soil can dissolve in a drain. However, the only products that will successfully dissolve the clumped soil are not available for purchase by anyone but professionals.

One of these products is called sulfuric acid and can easily dissolve the soil and other similar substances. If no other method has worked and you think this might be your best option, it’s a good idea to contact a plumber for advice.

It’s usually best not to use this option if your drains are made of the following materials:

  • Steel
  • Aluminum
  • Galvanized Steel

Tips to Keep the Soil in the Pot and Avoid Clogging

Sometimes potting soil washes down the drain when you are watering your plants.

If you use the sink when watering your plants and leave them to drain excess water, you’ll want to take several measures to keep soil from going through the pot’s drainage holes and clogging your drains:

Use a Pot With Many Small Holes

Drainage holes help prevent root rot, suffocation, and salt buildup in the soil. 

Unfortunately, the pots with drainage holes allow the soil to pass through when you water the plants. One way to ensure you don’t lose soil is to use a pot with many small holes that allow water through while the dirt remains in the pot. 

Add a Coffee Filter at the Base

Before adding potting soil to the planter, line the base with a coffee filter or a fine mesh screen. The coffee filter is light enough to allow water to pass through, but it will block the soil. 

If the plant is already in the pot, you can still line the coffee filter outside the pot by covering the drainage holes. Unfortunately, these pots are much harder to handle, and you may need to bottom water your plants instead of pouring water into the soil.

Fill the sink with water and place your potted plants in it. Allow them to sit for 10 minutes as you bottom water your plants. The mesh grid prevents soil from passing through the drainage holes. 

Check the soil by digging your finger into it. If it’s still dry up to your first knuckle, give it a few more minutes. The process usually takes 10-30 minutes, but it can vary depending on pot size and soil type. Adding a mesh grid on the drainage hole can further slow down the process.

Use Removable Saucers

Removable saucers collect excess water that drains out of the potting soil. The pot sits on them, so no dirt escapes from the drainage holes. However, you must ensure that the pot doesn’t sit on the saucer for too long, as the wet soil will stick on and block the drainage holes.

Plants in pots with blocked drainage holes are not different from those planted in pots with no drainage holes. Soon, the water collecting at the base will cause the roots to rot, so avoid buying pots with attached drainage saucers. They will also eventually cause the soil to cover the drainage holes. 

Line the Draining Saucer

Another option is to layer the draining saucer with pebbles or sand, but avoid using gravel and rocks because they stick together and prevent the free movement of water. 

Place the pot over the layered saucer. The water in the sand or pebbles will evaporate, but the base will remain moist enough to keep the atmosphere around the foliage cool.

This method has two main benefits:

  • It prevents the loss of soil when watering plants. 
  • It provides humidity to plants exposed to high temperatures. 

Don’t Overwater the Plants

Potting soil often leaks through the drainage holes because you overwatered the plant. When watering potted plants, you should do it until the water starts dripping through the drainage holes. However, you should be careful, because you want the soil moist, not wet. 

Avoid Force and Speed When Watering Potted Plants

There is such a thing as watering plants too fast. Many people don’t realize that soil needs time to absorb the water and that water can pass through without soaking the soil. 

Pour water into the pot slowly, giving the soil a chance to soak up the water. 

You can monitor how the soil absorbs the water by observing the draining saucer. If it takes a long time for the water to collect at the base of the pot, then your potting soil has absorbed the water. You’re unlikely to lose soil through the drainage holes when you water your plants slowly. 

This video gives tips on how to water your potted plants.

The Best Ways to Dispose of Old Potting Soil

There are many ways to dispose of old potting soil but flushing it down the sink is definitely not one of them. If your potting soil isn’t in the best shape and you know you can’t reuse it for one reason or another, you can always take it down to your local landfill or a specialized soil recycling center. 

These soil recycling centers often ask for a small amount of money to test your soil to ensure that it isn’t contaminated, but this is often a better choice than the landfill because at least you’ll know the soil will be reused.

However, you may not even have thought that you can actually upcycle the soil, even if it’s not in the best condition. 

Here are some eco-friendly and economical options:

Block Pest Burrows

Reusing your potting soil is an excellent way to reduce unnecessary waste and allows you to save money elsewhere. This is what many seasoned gardeners choose to do since it prevents them from buying new soil.

If your soil is contaminated with disease or infestation, you can use it to refill holes in the garden created by moles. This means you don’t need to rake your garden to pull the soil over the holes, as you can just refill them with upcycled soil. 

Sterilize and Mix With New Soil

If your soil is still in decent condition, it’s best to buy another potting soil mixture and use a half-and-half mixture of the two batches.

For best results, follow the steps below to reuse it:

  1. Spread your old potting soil across a tarp or other surface. 
  2. Take a fresh mass of potting soil and mix them 50/50 until they’re well combined. 
  3. Leave the soil mixture in the sun for a few hours before using.
  4. Refill your pots as usual.

Add to the Compost Pile

You can put old potting soil in compost. The only issue is that, once the compost has been utilized, you will find little pieces of perlite leftover that you’ll have to dispose of. Other than that, throwing your old potting soil in compost is a great way to upcycle and will benefit your garden. 

While adding potting soil to compost is an excellent idea, you should always ensure that the soil isn’t infested with insects or diseased. Those infestations can always infect other areas in your garden and won’t go away just because you’re using the soil for something else.

An excellent way to prevent this problem is to leave your potting soil somewhere warm in the sun for a few days. This allows anything unwanted living in the soil to dissipate, leaving you with valuable, dry soil that will help you maintain the rest of your garden throughout the rest of the year.


Potting soil is different from the soil in your garden because the potting mix is not just made up of soil. It also has organic matter that decomposes over time.

Some materials, such as tree bark, help with mulching and moisture retention. You don’t want these materials to clog the drain. The damage may extend through the entire plumbing system, resulting in costly repairs.

Dr. Moritz Picot

Dr. Moritz Picot is a horticulture enthusiast and the founder of TheGrowingLeaf.com, where he serves as the lead content writer. He established the website in 2022 as a valuable resource for both gardening aficionados and beginners, compiling all the gardening tips he has accumulated over the past 25 years. Alex has a passion for nurturing plants, transforming backyards into inviting spaces, and sharing his knowledge with the world.

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