How to Clear a Blocked Drain

Blocked drains are one of the most common issues in the home.

They often begin with small signs, like water draining more slowly than usual, a bad smell near the sink, or a faint gurgling sound in the pipes.

At first, it may not seem serious. But over time, the blockage can build until the drain stops working properly. If left too long, blockages can lead to more serious issues, including pipe damage and costly repairs. 

Knowing what to do early makes it much easier to fix. 

Quick Guide: How to Clear a Blocked Drain

Follow these steps in order, starting with the simplest method first.

Check the drain
See if the water is draining slowly or not at all.

Remove standing water
Clear any water so you can reach the blockage.

Clear the drain opening first
Pull out hair, food or build-up near the drain opening.

Flush with hot water
Pour slowly in stages to loosen grease and soap build-up.

Use a natural cleaner
Try baking soda and vinegar to break down light blockages.

Try a grease break-down method
Use dish soap and hot water if the blockage is in a kitchen sink.

Use a plunger
Create pressure to loosen soft or stubborn clogs 

Use a drain tool or snake
Remove deeper clogs like hair or build-up stuck further down the pipe. 

Check the pipe under the sink
Clear the trap if the blockage is still there.

Watch for repeat blockages
If the blockage keeps coming back, the issue may be deeper in the pipe.

How to Clear a Blocked Drain (Step-by-Step)

Start with the simplest method and work your way down. Many blockages can be cleared early without needing anything complex.

Step 1: Check the drain

Start by looking at how the water is behaving.

• If it drains slowly, the blockage is likely building up
• If it doesn’t drain at all, the blockage may be more solid or deeper

This helps you decide which step to try next. 

Step 2: Remove standing water

If water is sitting in the sink, shower or laundry, remove as much as you can first.

You can use:

• A cup or jug
• A small bucket
• Old towels

This allows your cleaning method to reach the blockage directly instead of sitting on top of the water.

Step 3: Remove what’s stuck near the drain

Many blockages sit close to the drain opening.

You might find:

• Hair
• Food scraps
• Soap build-up

You can use:

• Gloves
• A plastic drain tool (used to pull out hair) 
• A straightened wire hanger

Pull slowly and carefully so you don’t push the blockage further down.

Step 4: Flush with hot water

Hot water can help break down grease, soap and light build-up.

• Boil a kettle and pour slowly
• Do this in 2-3 stages
• Wait a few seconds between pours

If you have plastic pipes, use very hot tap water instead of boiling water.

This step works well for kitchen sinks and bathroom basins.

Step 5: Use a natural cleaner

This is a simple method for slow drains and minor build-up.

You can try:

Baking soda and vinegar

• Pour ½ to 1 cup of baking soda into the drain
• Add 1 cup of white vinegar
• Cover the drain
• Leave for 15-30 minutes
• Flush with hot water

You may need to repeat this if the build-up is heavier.

Step 6: Try a grease break-down method

If the blockage is in a kitchen sink, grease is often the cause.

• Pour a generous amount of dish soap into the drain
• Let it sit for a few minutes
• Flush with hot water

This helps break down oil and grease stuck to the pipe walls.

Step 7: Use a plunger

A plunger can help shift soft or stubborn blockages. 

• Add enough water to cover the plunger cup
• Place it firmly over the drain to create a seal 
• Push and pull quickly for 20-30 seconds
• Test the drain

If your sink has a small overflow hole near the top, cover it with a cloth to create a better seal. 

Step 8: Use a drain tool or snake

If the blockage is deeper, a drain tool can help remove it.

A drain tool is a thin plastic strip with small hooks that grab hair and build-up.

A drain snake is a longer, flexible tool that can reach further into the pipe to break up or pull out blockages.

• Insert the tool slowly into the drain
• Twist gently as you push forward
• Pull it back out
• Remove any build-up
• Flush with hot water

This is especially effective for hair clogs and deeper build-up. It works best when the blockage is not too far down the pipe.

Step 9: Check the pipe under the sink

If the problem continues, the blockage may be sitting in the pipe underneath.

• Place a bucket under the pipe
• Unscrew the trap carefully
• Remove and clean out any build-up inside the pipe 
• Reattach the pipe
• Run water to check the flow

This is a common spot for grease and food build-up.

Step 10: Watch for repeat blockages

If the drain keeps blocking, there may be a deeper issue.

This can include:

• Build-up further down the pipe
• Tree roots
• Pipe damage
• A blockage in the main line

At this point, basic home methods may not fully solve the problem. 

When Basic Methods Don’t Work

If the steps above don’t clear the blockage, the problem may be deeper in the pipe.

In some cases, a stronger method may help. If the problem continues, more advanced tools may be needed. 

Chemical drain cleaners

Chemical cleaners are available from hardware stores and supermarkets.

You can use these as a next step when basic methods haven’t worked, but they should be used carefully. 

• Can dissolve grease, hair and food build-up
• Should be used carefully and not too often
• Can be harmful to pipes, surfaces and the environment
• Always follow safety instructions and avoid contact with skin or eyes
• Wear gloves and take care to avoid splashes when using these products
• Not effective for solid blockages like tree roots or objects stuck in the pipe

After use, flush the drain with water to clear any remaining chemicals.

Chemical drain cleaners should only be used occasionally, as repeated use can damage pipes over time.

Drain snake (or flexible drain tool) 

A drain snake (also called an electric eel) is used for deeper blockages. It works by reaching further into the pipe to break up or pull out the blockage.

• Breaks up or pulls out build-up
• Reaches further into the pipe than surface tools
• Useful for hair, food waste and stubborn clogs
• Has limited reach, so it works best when the blockage is not too far down the pipe

Care should be taken to avoid forcing the tool, as this can damage the pipe.

If you’re unsure or the blockage doesn’t clear, it’s often safer to have a plumber handle it properly. 

High-pressure water (hydro-jetting)

Hydro-jetting uses a strong stream of water to clear pipes. It is used to flush out build-up and clean the inside of the pipe walls.

• Pushes blockages through the system
• Cleans the inside of the pipe walls
• Can remove grease and build-up along the pipe
• More effective for build-up than solid obstructions

Because this method uses high pressure and specialised equipment, it’s usually best carried out by an experienced plumber to avoid damage and ensure the blockage is fully cleared. 

CCTV drain inspection

Cameras can be used to inspect inside pipes. This method is used to find the exact cause of a blockage when it is not clear.

• Helps locate the exact cause of the blockage
• Identifies damage, roots or structural issues
• Used when the problem is not clear or keeps returning

This helps identify the exact issue before deciding on the right fix.

Excavation and pipe repair

In severe cases, your pipe may need to be repaired or replaced. This is used when the blockage is caused by damage that cannot be cleared from inside the pipe.

• Used when pipes are damaged or collapsed
• Required for major root intrusion or structural issues
• Involves digging to access the affected section
• Allows damaged sections of pipe to be repaired or replaced to restore proper flow

This is usually the last step when other methods can’t fix the problem, as it involves more complex work. At this point, the issue needs to be located and repaired at the source, so it’s best handled by a qualified plumber. 

Prevention Tips

Blocked drains are often caused by everyday habits. Small changes can help stop build-up before it turns into a blockage.

In the kitchen

• Do not pour grease or oil down the sink
• Let fats cool and dispose of them in the bin
• Scrape food scraps into the bin before rinsing dishes
• Use a sink strainer or drain cover to catch anything that gets through
• Run hot water after washing dishes, especially after cooking

In the bathroom

• Use a hair catcher or drain cover to stop hair going down the drain
• Remove hair from the drain regularly
• Avoid letting soap, toothpaste and products build up
• Rinse the drain with hot water after use
• Act early if water starts draining slowly

Around the home

• Keep outdoor drains clear of leaves, dirt and garden waste
• Check drains after heavy rain or storms
• Avoid washing soil, sand or loose material into drains
• Only flush toilet paper and human waste

Monthly maintenance

• Flush kitchen and bathroom drains with hot water
• Use baking soda and vinegar on slow drains
• Clean sink strainers and shower covers
• Check and clean the pipe under the sink if needed

Signs of a Blocked Drain

Blocked drains rarely happen all at once. In most cases, there are early warning signs that are easy to miss.

Many homeowners overlook these early signs, but they’re often the first sign that something is building inside the pipe. The longer a blockage is left untreated, the more it builds and the harder it becomes to clear. 

Knowing what to look for can help you act early and avoid a bigger problem.

Bad smells from the drain

A bad smell is often one of the first signs.

When water and waste get trapped, bacteria begin to grow. As this build-up breaks down, it creates a strong, unpleasant odour. As the blockage sits, the smell can become stronger and more noticeable over time. 

You may notice:

• A sour or rotten smell near the sink or shower
• A smell that gets stronger after using water
• Odours that come and go throughout the day

In many cases, the smell appears before any visible signs of a blockage.

This usually means water and waste are sitting inside the pipe instead of flowing through. 

Water backing up or overflowing

Water pushing back up through the drain is a clear sign of a blockage.

At first, it may:

• Rise slightly, then drain away
• Pool around the drain before clearing

Over time, this can turn into:

• Water sitting in the sink or shower
• Overflow during normal use

If water is coming back up, even briefly, it usually means the blockage is already restricting flow inside the pipe.

Even if it seems minor, it will usually get worse as the blockage builds.

Gurgling or bubbling sounds

Gurgling sounds often mean air is trapped in the pipe.

This happens when water tries to move past a blockage and pulls air through at the same time.

You might notice:

• A “glugging” sound after water drains
• Noises coming from nearby pipes or drains
• Sounds even when you’re not using that tap, sink or shower

These sounds are often more noticeable when using more than one tap, sink or shower at the same time.

This is a sign that the flow inside the pipe is restricted.

Water draining slowly

Slow drainage is one of the most common early signs.

Water may:

• Take longer to drain from sinks or showers
• Sit briefly before going down
• Leave a thin layer behind

This usually means build-up is forming along the inside of the pipe, reducing the space for water to flow.

It may not seem urgent at first, but it almost always gets worse over time.

Water appearing in other drains

If water shows up in a different drain, the blockage may be deeper in the system.

For example:

• Flushing the toilet causes water to rise in the shower
• Running the washing machine makes the laundry drain bubble

This is often a sign that the blockage is affecting shared pipework, not just one drain.

This usually means the blockage is further down the pipe and affecting multiple fixtures.

Repeat blockages

If the same drain keeps blocking, it’s a sign the issue hasn’t been fully cleared.

This can be caused by:

• Build-up further down the pipe
• Grease or build-up lining the inside of the pipe
• Tree roots or damage underground

In many cases, repeat blockages point to an underlying issue rather than a one-off clog.

This usually means the problem needs more than a quick fix.

Common Causes of Blocked Drains

Blocked drains are usually caused by everyday materials building up over time.

In most homes, it’s not just one thing. It’s a combination of grease, build-up and waste slowly collecting inside the pipe until water can no longer flow properly. 

Understanding what causes blockages can help you choose the right fix and prevent the same problem from happening again.

Build-up from everyday use

Some of the most common blockages come from things that go down the drain every day.

Grease, fats and cooking oil
Grease and oil may go down as liquid, but they cool and harden inside the pipe. Over time, they stick to the pipe walls and trap other build-up, forming a thick blockage. 

Food scraps and residue
Small food particles, coffee grounds and tea leaves may seem harmless, but they can collect inside the pipe and clump together. As more waste builds up, it becomes harder for water to pass through.

Soap and product residue
Soap, shampoo and other products can leave a film inside pipes. This residue sticks to the pipe walls and creates a surface for hair and build-up to cling to. 

Mineral build-up
Water contains natural minerals that can coat the inside of pipes over time. This reduces the space for water to flow and makes it easier for other materials to get stuck.

Hair and bathroom waste

Bathroom drains are especially prone to blockages.

Hair build-up
Hair is one of the most common causes of blocked drains. It easily tangles and collects in the pipe, especially when combined with soap and conditioner.

This includes:

• Long hair
• Short hair and shaving residue
• Pet hair

Over time, this forms dense clumps that restrict water flow.

Items that should not be flushed or washed away

Many blockages are caused by items that don’t break down properly.

Toiletries and hygiene products
Items like wipes (even those labelled “flushable”), nappies and sanitary products do not dissolve in water. They can become stuck in pipes and create serious blockages.

In most cases, only toilet paper and human waste should be flushed. 

Foreign objects
Toilets and drains can easily collect objects that are dropped or flushed accidentally. These can become lodged in bends in the pipe and block the flow completely.

This is more common in households with young children.

Cat litter
Cat litter is designed to absorb and clump. When flushed, it expands and hardens inside the pipe, making it very difficult to remove.

All types of cat litter should be disposed of in the bin, not flushed. 

Outdoor and environmental causes

Some blockages come from outside the home.

Tree roots
Tree roots can enter underground pipes through small cracks or joints. Once inside, they grow and spread, eventually blocking the pipe and causing damage.

As they grow, they can also damage the pipe itself, which usually requires professional repair. 

Natural garden waste

Leaves, soil, dirt and small branches can enter outdoor drains, especially during storms. Over time, this build-up restricts water flow.

Why blockages get worse over time

Most blockages don’t happen straight away.

A small amount of build-up might not cause a problem at first. But as more material collects, the pipe becomes narrower and water flow slows down.

This makes it easier for even more build-up to get stuck. 

Over time, what started as a minor issue can turn into a full blockage.

FAQs

What causes a blocked drain in the first place?

Blocked drains are usually caused by build-up inside the pipe. This can include grease, food scraps, hair, soap and other materials that collect over time. In some cases, the problem may be caused by tree roots, damaged pipes or items that should not have been flushed.

What is the most common cause of blocked drains in bathrooms?

The most common cause of bathroom blockages is hair combined with soap and product build-up. Hair easily tangles and collects inside the pipe, forming clumps that restrict water flow.

What causes bad smells from a drain?

Bad smells are usually caused by water and waste sitting inside the pipe.

As this build-up breaks down, it creates odours that may come and go or become stronger after using water. 

What is the best way to clear a blocked drain at home?

Start with the simplest steps first. Remove anything stuck near the drain opening, flush with hot water, and try a natural cleaner.

If the blockage remains, you can use a plunger or a drain tool to remove deeper build-up.

Can boiling water clear a blocked drain?

Hot or boiling water can help loosen grease and soap build-up, especially in kitchen sinks.

It works best for light blockages, but it won’t clear solid clogs. For plastic pipes, use very hot tap water instead of boiling water.

Is it safe to use boiling water on all drains?

Boiling water can help break down grease and soap, but it should be used with care. For metal pipes, it is generally safe. For plastic pipes, very hot tap water is a better option, as boiling water can loosen joints over time.

Does baking soda and vinegar work on blocked drains?

This method can help break down light build-up and reduce smells. It’s a good option for slow drains, but it may not clear a fully blocked pipe on its own.

Are chemical drain cleaners safe to use?

Chemical cleaners can break down grease and build-up inside the pipe, but they should be used carefully.

Using them too often can damage pipes and may not work on solid blockages like tree roots or objects stuck in the pipe.

Why does my drain keep blocking even after I clear it?

If a drain keeps blocking, the underlying issue may not have been fully removed. There may be build-up further down the pipe, grease lining the pipe, or a structural issue such as tree roots or damage.

Can a blocked drain fix itself?

In most cases, a blocked drain will not fix itself. While water may slowly drain over time, the build-up inside the pipe usually remains and continues to get worse.

How can I prevent blocked drains in the future?

Simple habits can help prevent blockages. Avoid pouring grease down the sink, use drain covers to catch hair and food, and clean your drains regularly. Acting early when you notice slow drainage can also prevent bigger problems.

When should I call a plumber for a blocked drain?

You should consider contacting a plumber if you’ve tried a few methods and the problem keeps coming back, or if the blockage affects multiple drains.

Water backing up or slow drainage that doesn’t improve are clear signs of a deeper issue that needs proper inspection and repair.

Trust Fluid for Your Plumbing Needs

Do you have a stubborn blocked drain? Call Fluid for Plumbing on the Central Coast & Newcastle to clear your drains. We are highly skilled at what we do and have the experience to handle just about any problem you can throw at us. We welcome you to get in touch with us to learn more about our services and how we can help you keep your drains flowing smoothly at all times. Call us today to schedule an appointment.