Photo of a blocked drain and person using a plunger.

10 Most Common Causes of Blocked Drains and How to Fix Them

Do you have blocked drains in your home or business? If so, you’re not alone. Clogged and blocked drains are a common problem, but fortunately, they can usually be fixed relatively easily. If you’re dealing with blocked drains, read on to learn what could be causing the issue and how you can get your drains flowing again.

Fun fact: the record for the largest item ever removed from a blocked drain was a giant 9-foot python in Queensland, Australia! So it’s worth being mindful of what could be lurking down there if you have a blocked drain.

Here’s the top ten causes of blocked drains and how to fix them:

1) Grease, fat, and oil

One of the most common causes of blocked drains in the kitchen is grease, fat, and oil. Grease, fat, and oil can easily become stuck in pipes and clog up drains. This is especially true when large amounts are poured down the drain or flushed down the toilet. To avoid having blocked drains due to grease, fat, and oil, it’s best to not pour them down the drain at all. Instead, wipe them up with a paper towel and throw them away in the trash. Additionally, you can also put oil and grease into a plastic container and dispose of it with your regular waste.

It can also be useful to pour one to two cups of boiling water from your kettle down the sink to help keep the drain clean. This will help to melt any grease, fat or oil and keep the drain clean.

If you’ve got a blockage in the kitchen sink that won’t budge, a licensed plumber may need to use a high pressure jetter to clear away the blockage.

2) Soap scum

We’ve all experienced it – that slimy, slippery layer of soap scum that seems to form on our plumbing fixtures. But did you know that it can also lead to blocked drains? That’s right – soap scum can cause drainage problems if it accumulates in the pipes.

Soap scum is made up of tiny particles that build up over time, preventing water from flowing freely through your pipes. It can also become a breeding ground for bacteria and other microorganisms that can lead to clogs.

Fortunately, there are a few simple steps you can take to prevent this problem. First, you can install an aerator on your tap, which helps reduce the amount of soap scum that gets into your plumbing. You should also use a drain cleaner every month or so to break down any existing soap scum before it builds up. Finally, you may want to call a professional plumber if you notice signs of a more serious clog. A plumber can inspect your pipes and provide you with expert advice on how to keep your drains running smoothly.

3) Tree roots

Tree roots can be a tricky issue when it comes to plumbing. They can easily enter your pipes and cause a major blockage, leaving you with a frustratingly blocked drain. In most cases, the only way to get rid of the blockage is to call a professional plumber. A plumber can use specialized tools and techniques to remove the tree roots and restore your plumbing system to normal. It’s important to act quickly if you think tree roots might be causing the blockage, as they can continue to grow and create bigger and bigger problems for your drainage system. At Plumbing Bros, we use a drain camera, in conjunction with an above-ground locator to pin point exactly where the blockage is, so we can advise the best way to remove the blockage (and make sure that if we need to dig up the pipe, we’re only digging where we need to!).

4) Coffee grounds

Coffee grounds can quickly accumulate in drains and form a clog, resulting in a blocked sink or shower drain. To avoid this, it’s important to always dispose of your used coffee grounds responsibly – don’t pour them down the drain! If you’re looking for an easy fix for a blocked drain, try removing as much of the built-up coffee grounds as you can with a plunger, before pouring hot water down the drain to flush out any remaining grounds. If this doesn’t work, you may need to call in a professional to help you unclog your drain.

5) Hair

It happens to us all – your shower drain suddenly becomes blocked and you’re left scratching your head trying to figure out the cause. In many cases, the culprit is hair! Whether it’s yours, your partner’s, your pets’, or even your guests’, hair can easily make its way down your drain, clumping up and blocking the flow of water. The best way to fix this issue is to stop it before it happens – take extra care when washing your hair and make sure that as little as possible makes its way down the drain.

If you’ve already got a blockage on your hands, try using a drain cleaner to break up the clog, or a plunger to push it down the line. If these options don’t do the trick, it might be time to call in a professional plumber. They’ll have the tools to remove the blockage quickly and easily, so you can get back to your normal shower routine.

6) Sanitary products

Sanitary products are a common cause of blocked drains, so it’s important to keep them out of your drain at all costs. Toilet paper is designed to break down and flush away quickly, but sanitary products can be tougher to move through pipes. That means they can get caught in the trap or pipe junction and cause a blockage. It’s best to dispose of sanitary products in the bin rather than flushing them away. If you have a blockage due to sanitary products, contact a professional plumber for help. They will be able to help you clear the blockage without damaging your pipes.

7) Food waste

Food waste is one of the biggest culprits when it comes to blocked drains. While it might seem harmless, food scraps can quickly build up and cause major issues. If you’re regularly cooking up a storm in the kitchen, you need to be mindful of what goes down the sink. Avoid flushing down anything other than water, as food scraps can easily stick to the sides of pipes and create blockages. If you do find yourself with a blocked drain due to food waste, a plumber should be able to help unblock it for you. Alternatively, you can try using a plunger or vinegar and baking soda to help break it up and clear the blockage.

8) Toys

It may seem hard to believe, but it’s not uncommon for kids’ toys to end up in your drains. Kids are always leaving their toys lying around, and if you’re not careful, they can easily get washed away. This can cause your drains to become blocked and water to start backing up. The best way to avoid this problem is to be vigilant about checking for any objects that could fall into the drain, especially if you have young kids in the house. If you do find a toy stuck in the drain, you’ll need to remove it before you can unblock the drain. The easiest way to do this is to use a pair of pliers or tongs to grab hold of it and then pull it out.

9) Dirt and mud

It’s not uncommon for dirt and mud to make its way down your drains, especially during the wetter seasons. Over time, this can accumulate and create blockages in your pipes. The best way to avoid this problem is to ensure that your outdoor drains are properly covered, as this will stop dirt and mud from entering the system in the first place. You should also regularly inspect and clean your outdoor drains, making sure any debris or gunk is cleared away. If you do find that you have a blockage, you may need to hire a plumber to come and clear it for you.

10) Leaves

Fallen leaves can be a major cause of blocked drains. When the leaves collect in your gutter, they may be washed down into the drains and eventually form a clog. To prevent this from happening, be sure to regularly clean out your gutters and remove any leaves or debris that have collected there. If you notice that the water is taking longer than usual to drain, it could be due to a blockage caused by leaves. In this case, the best way to fix the issue is to call a plumber and have them snake the drain to remove the blockage. Doing this promptly can save you a lot of hassle and money in the long run.


Blocked drains can be a hassle and can even cause serious damage to your property if not dealt with quickly. While many common causes of blocked drains, such as grease, fat, and oil, can be prevented with proper care and maintenance, other causes, such as tree roots and food waste, are out of our control. Fortunately, there are solutions to every problem. From using chemical drain cleaners to calling a professional plumber, you’re sure to find the right fix for your particular issue. With a little effort and patience, you can have your drains running freely again in no time!

Need to book a plumber to help with your blocked drains? Find your local Plumbing Bros team!