Gurgling Drains: 7 Scenarios And What Each One Is Telling You

We all know what it sounds like – odd, throaty. That deep gurgle coming from your sink or shower or toilet is one of those sounds that’s easy to ignore … right up until it isn’t. Gurgling drains are your plumbing system’s way of politely – or impolitely – telling you that air is moving somewhere it shouldn’t be. And depending on which drain is doing it, when it happens, and what else is going on in the house, that gurgle can mean anything from a minor annoyance to a sign that something more serious is developing underground.

Here are the 7 most common gurgling scenarios – and what each one actually means. And, better still, what you can or should do about it.

1. One sink gurgles when you run the tap

If a single sink gurgles only when you’re using it, the most likely cause is a partial blockage in that specific drain line. As water tries to pass the obstruction, air gets trapped and forced back up through the trap, creating the gurgle.

WHAT TO DO: Try a manual clear first – a plunger or a drain snake for minor blockages.

If the gurgling persists or returns quickly after clearing, the blockage may be further down the line than a DIY attempt can reach, and it’s worth getting a licensed plumber to inspect with a CCTV drain camera.

2. Drains gurgling in house whenever another fixture is used

Is this the pattern with gurgling drains in your house?:

• You flush the toilet
• The bathtub gurgles.

Or:

• You run the washing machine
• The laundry sink burps.

You get the idea – it’s what happens when multiple fixtures share a common drain line and a blockage somewhere in that shared line is forcing air backward into whichever fixture has the least resistance.

WHAT TO DO: This is a sign the blockage isn’t isolated to one fixture – it’s in a shared section of pipe. A CCTV drain inspection is the right next step to locate exactly where the blockage sits before any clearing work begins.

3. All drains in the house are gurgling at once

When every drain in the house – sinks, showers, toilets – starts gurgling around the same time, the problem has moved beyond an individual fixture or branch line. This points to a blockage or restriction in the main sewer line, or a problem with the vent stack that’s supposed to let air in and out of the system to equalise pressure.

WHAT TO DO: This scenario warrants a professional inspection sooner rather than later.

A blocked or damaged main line affects the entire property’s drainage, and continuing to use fixtures while it’s blocked increases the risk not only of a gurgling drain, but a serious backup. Get a licensed plumber out for a full system assessment.

4. Why are my external drains gurgling?

We’ve talked about the internal drains, but what about the external ones?

• Stormwater pits
• External grates
• Yard drains.

If they gurgle, particularly during or after rain, that usually indicates a partial blockage or restriction somewhere in the stormwater or combined drainage system.

Leaves, silt, and debris accumulate in outdoor lines over time and create exactly the kind of restriction that produces this sound when water tries to move through under pressure.

WHAT TO DO: Clear visible debris from grates and pits where accessible. If the gurgling continues despite a clean surface, the blockage is likely further into the line and needs a professional drain cleaning – often with high-pressure water jetting to fully remove compacted material.

5. Gurgling drains after heavy rain

Do you live in a place with particularly intense wet seasons? Gurgling after heavy rain is therefore very common – but it rains all over Australia, so the gurgling happens everywhere too!

When drains – especially ground-floor or external ones – gurgle specifically after heavy rain, it’s often because the stormwater or sewer main is under significant pressure from the volume of water entering the system. As the main struggles to cope, air gets pushed back through your connections, producing the gurgle.

WHAT TO DO: Occasional gurgling during extreme rain events isn’t necessarily a property-specific problem – it can reflect strain on the broader council network.

But if it happens with every moderate rain event, or if it’s accompanied by slow drainage or backflow, it suggests your property’s connection or a reflux valve (if one is fitted) needs assessment.

6. Gurgling that comes with a bad smell

Gurgling combined with a foul sewage odour is a step beyond a simple airflow issue. This combination often points to a drying trap – water has evaporated from a rarely-used drain (like a guest bathroom or laundry floor drain), breaking the seal that normally blocks sewer gas from entering the home – or a more significant blockage that’s allowing gas to escape back through the system.

WHAT TO DO: Run water through any rarely-used drains to refill the trap and see if the smell resolves. If it persists, or if multiple drains are affected, treat this as a sign of a genuine blockage or vent issue requiring professional diagnosis.

7. New or worsening gurgling with no obvious trigger

Sometimes gurgling develops gradually with no clear cause – no recent heavy rain, no specific fixture pattern, just a sound that’s become more frequent over weeks or months.

This is usually the result of a slow-developing blockage:

• A tree root intrusion
• Gradual scale buildup
• Or a partially collapsed section of pipe – that’s been getting worse incrementally.

WHAT TO DO: Don’t wait for it to become an emergency. A CCTV drain inspection at this stage can catch a developing problem while it’s still a straightforward fix, rather than after it’s progressed to a full blockage or pipe failure.

How to fix gurgling drains – And when to call a pro

Simple, isolated gurgling at a single fixture is often resolved with basic clearing methods.

Have you tried:

• A plunger?
• A simple drain snake?
• A kettle of hot water poured slowly down the drain?

Sometimes, that’s enough to clear a simple, isolated gurgle at a single fixture.

But anything involving multiple fixtures, the whole house, recurring patterns after rain, or accompanying smells is a sign of a more significant issue that needs proper diagnosis – usually starting with a camera inspection rather than guesswork.

Get connected with a trusted local plumber

Why are my drains gurgling? It’s something we’re asked all the time – and we know exactly who you should turn to. Best Plumbers Club connects you with reviewed, licensed local plumbers who can diagnose and fix gurgling drains properly – whatever the cause. No guesswork, no chasing quotes from multiple tradespeople. Find out how easy it is by calling or requesting a quote online today.