What Causes Gurgling Sounds in Sinks and Toilets?

You’re standing in the kitchen or bathroom and suddenly you hear it. That strange gurgling noise coming from the sink or toilet. It might only last a few seconds, but it’s enough to make you wonder what’s going on inside your pipes.

In most Adelaide homes, gurgling plumbing isn’t just a random sound. It’s usually a sign that air is being forced through the drainage system due to a developing blockage, venting issue, or pressure imbalance. While everything might still seem to be draining, those noises are often an early warning that something isn’t working the way it should.



Ignoring it can allow a minor issue to turn into a full blockage or even a messy backup. Understanding what causes gurgling sounds in sinks and toilets can help you act early and avoid bigger plumbing problems down the track.

What Does a Gurgling Sound in Plumbing Mean?

Why Does My Sink Make a Gurgling Sound?

If your sink is making a gurgling sound, it usually means air is struggling to move through the drainage system properly. That airflow disruption is often caused by a blockage or pressure imbalance somewhere in the pipes. Even if water is still draining, the noise is a sign that something is starting to build up.

Here are the most common reasons sinks begin to gurgle:

Partial Drain Blockage

One of the most frequent causes is a partial blockage in the waste pipe. In bathroom sinks, this is usually hair, soap residue and toothpaste buildup. In kitchen sinks, it’s often food scraps, grease and cooking oils. 

When water tries to flow past this restriction, it creates suction. Air gets pulled through the water in the trap, which causes that bubbling or gurgling sound. If left untreated, the blockage will continue to grow until the sink drains very slowly or stops altogether.

Blocked or Restricted Vent Pipe

Your plumbing system relies on vent pipes, usually running up through the roof, to regulate air pressure. If that vent becomes blocked by leaves, debris or even nesting birds, air cannot move freely.

When this happens, negative pressure forms in the pipes. The system then pulls air through the nearest fixture, often your sink, creating a gurgling noise. If multiple fixtures are making noise, a venting issue is a likely cause.

If you suspect a blocked drain, arrange a blocked drain service in Adelaide with Best Plumbing Maintenence.

Issues Deeper in the Drain Line

Sometimes the problem is not directly under the sink. A developing blockage further down the main drain line can affect how air and water move through the entire system. In this case, you may notice other warning signs like slow drainage, unpleasant smells or gurgling from nearby fixtures.

Because these issues can escalate into full drain blockages or backups, it’s best to investigate early rather than wait for the sink to stop working completely. Call us on (08) 8261 0165 to book a service. 

"We have used them before but had Matt out recently for blocked pipes. He was on time, efficient and friendly. Got the pipes unblocked very quickly and the reception staff on the phone are lovely too. Highly recommend and will be our go to for anything needed in future."

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Why Does My Toilet Make a Gurgling Sound?

A gurgling toilet is usually a stronger warning sign than a noisy sink. Toilets connect directly to your main sewer line, so when you hear bubbling or gurgling, it often means there’s pressure building up somewhere deeper in the system.

Sometimes you’ll notice the toilet gurgles when you flush it. Other times, it might bubble when you run the sink, shower or washing machine. That crossover between fixtures is a clear sign the issue isn’t isolated. It’s usually happening further down the line.

Here are the most common causes.

Main Sewer Line Blockage

One of the biggest culprits is a developing blockage in the main sewer line. This can be caused by wipes, excessive toilet paper, grease buildup or foreign objects.

As wastewater tries to push past the obstruction, air gets trapped and forced back up through the nearest opening, often your toilet bowl. That’s what creates the bubbling or gurgling sound.

This type of blockage can escalate into sewage backing up into your home. If you suspect this may be the issue, it’s best to arrange professional sewer drain clearing through our blocked drains in Adelaide service before it becomes an emergency.

Tree Root Intrusion

In many Adelaide suburbs, especially areas with established trees and older pipework, tree roots are a very common cause of sewer issues. Roots naturally seek moisture and can enter tiny cracks in underground pipes. Over time, they grow inside the line and restrict flow.

This creates turbulence and air pockets in the system, which often show up as a gurgling toilet. A drain camera inspection can confirm whether roots are the cause and identify exactly where the pipe is affected.

You can learn more about how this works through our CCTV drain inspection service.

What to expect when tree roots are the problem?

Blocked or Faulty Vent Pipe

Just like sinks, toilets rely on proper venting to maintain pressure balance. If the vent pipe is blocked, the system cannot draw in air correctly. The toilet may then pull air through the water in the bowl, causing bubbling sounds.

If you notice fluctuating water levels in the bowl along with gurgling, this may point to a venting issue rather than a simple blockage.

Why Does My Sink Gurgle When I Flush the Toilet?

If your sink gurgles when you flush the toilet, it usually means the two fixtures are connected to the same drainage line and there’s a pressure problem somewhere in the system.

When you flush the toilet, a large volume of water rushes into the drain at once. If the pipe is partially blocked or the venting system isn’t working properly, air can’t move freely through the line. That trapped air gets pushed or pulled through the nearest opening, which is often your sink. As it moves through the water sitting in the sink’s trap, it creates that bubbling or gurgling sound.

In simple terms, your plumbing system is struggling to breathe.

This can happen for a few reasons. A developing blockage in the main drain line is common. Tree roots, built up debris or wipes can restrict flow and create pressure changes when the toilet is flushed. A blocked roof vent can cause the same issue by preventing air from entering the system to balance pressure.

If it only happens once, it may not be urgent. But if it continues or you notice slow drainage, unpleasant smells or changes in the toilet water level, it’s a sign the problem is getting worse. It’s best to have it inspected early before it turns into a full sewer blockage or backup.

Can You Fix Gurgling Pipes Yourself?

In some cases, you might be able to fix minor gurgling yourself. If the noise is coming from a single sink and the drain is only slightly slow, a simple plunger can sometimes clear a small surface blockage. Removing hair from a bathroom waste or cleaning out a visible trap under the sink may also help.

However, if the gurgling keeps coming back, affects multiple fixtures, or is happening when you flush the toilet or run other taps, it’s unlikely to be a quick DIY fix. That usually points to a deeper issue in the main drain line or a venting problem, both of which require proper diagnosis and equipment.

Chemical drain cleaners might seem like an easy solution, but they often cause more harm than good. They can damage pipes, especially in older Adelaide homes, and they rarely resolve larger obstructions like tree roots or compacted debris.

There’s also the legal side to consider. In South Australia, certain plumbing work must be carried out by a licensed professional. Attempting more complex repairs yourself can not only make the issue worse but may also affect insurance coverage if something goes wrong.

If the gurgling is persistent or you’re unsure what’s causing it, it’s safer to have it checked properly. Our team provides professional plumbing services in Adelaide and can identify the exact cause before it turns into a major blockage or backup.

A single, random gurgle might not mean there’s a serious problem. But if the noise keeps happening, gets louder, or starts affecting multiple fixtures, it’s time to take it seriously.

You should call a plumber if:

• Your sink or toilet gurgles regularly
• Multiple drains are making noise
• Water is draining slowly
• You notice unpleasant sewer smells
• The toilet water level rises or drops unexpectedly
• The problem started after heavy rain

These signs often point to a developing blockage in the main drain line, a venting issue, or even tree roots growing into underground pipes. The longer it’s left, the higher the risk of a full blockage or sewage backing up into your home.

The good news is that most drainage issues are far easier and cheaper to fix when caught early. A proper inspection can quickly identify whether it’s a simple obstruction or something deeper in the system.

If you’re hearing persistent gurgling sounds, don’t wait for it to turn into an emergency. Our team provides professional plumbing services in Adelaide and can diagnose whether the problem is a simple obstruction or something deeper within the sewer system. Acting early can prevent serious damage and messy backups. Call (08) 8261 0165 to schedule a visit.