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May 1, 2026While you are washing up or having a shower, all of sudden you hear that odd bubbling noise that comes from the drain. That annoying gurgling drain is usually a sign something is not quite right in your plumbing.
From many cases we’ve handled, the issue can be diagnosed early and fixed before it turns into a full blockage or overflow.
With this guide, our experts cover the main causes of a gurgling drain and what you can do to fix each one. Need immediate help to get it sorted straight away? Call our blocked drain specialists and they will step in and take care of it quickly.
Why Does a Drain Gurgle? (The Science Behind It)
When water flows through your pipes, air needs to move freely behind it to keep the pressure balanced and allow everything to drain smoothly.
So, if that airflow gets a blockage from a vent issue, air gets trapped inside the pipes. Then, that trapped air will force its way back up through the water and create the bubbling or gurgling sound you hear.
In short, not only does a drainage system help move water, it also relies on airflow to work properly.
Is It One Drain or Multiple?
Before attempting any fixes, let’s take a quick look at how widespread the issue is so you can narrow down the cause upfront.
- If only one drain is gurgling, then it usually points to a localised problem like a blockage in that specific pipe or a problem with the P-trap.
- If multiple drains are gurgling at the same time, this can signal a bigger issue like blocked vent pipe or a problem with your main sewer line.
- If your toilet gurgles each time you use the sink or shower, you can consider it as a strong sign of a main sewer issue. At this point, try to stop using water to prevent it turning into a backup. Simply get your plumber’s number to inspect it further.
What Causes Gurgling Drain?
Gurgling is caused by a blocked drainage system. When a single or several clogs occur, they interrupt the streamline of water and air, causing air bubbles to surface and producing a gurgling noise.
Gurgling drains commonly occur in the kitchen sink, shower, bathtub, and floor, sometimes requiring an easy fix. However, persistent drain gurgling could suggest a bigger problem in your house that needs help from professional Melbourne plumbers.
Now, let’s answer the question, “Why are my drains gurgling?”
1. Partial or Full Blockage in the Drain (Most Common Reason)
Two categories of drain blockages are partial and full, with both sharing common culprits like hair, soap scum, food scraps, grease, and even wet wipes.
The thing with a partial blockage is that water drains slowly and you will hear bubbling sounds as trapped air pushes through. Meanwhile, a full blockage stops water completely and can lead to pooling in sinks, showers, or tubs.
For a quick fix, you can try loosening the clog with a plunger. In case that doesn’t work, use a drain snake to pull out debris. Additionally, you can try pouring hot water mixed with dish soap to help break down grease build-up.
Unsure where or how to start? Check out our guide on how to unblock a drain as a walk-through for all the step-by-step basics.
2. Blocked Vent Pipe
One of the key roles of your vent pipe in your plumbing system is letting air move in and out so water can drain properly.
Thus, air simply cannot flow the moment these vents get blocked. In Melbourne homes, we often see vents blocked by leaves, bird nests, or even debris from possums. If you hear that gurgling sound, especially from multiple drains and those further away from the main vent, address it immediately.
Have access to the vent from ground level? We suggest you try flushing it with a hose. But for anything on the roof, it is much safer to call a plumber to protect you from a falling incident.
3. P-Trap Issue
The P-trap has that U-shaped pipe under your sink that holds a small amount of water. This water acts as a barrier that stops sewer gases from coming back up through the drain.
In rarely-used drains, the P-trap can get dried out or become damaged. That’s when you may hear gurgling along with unpleasant smells.
To keep the trap working as it should, remind yourself to run water through unused drains every week. Additionally, replace the trap that is cracked or loose.
4. Blocked Main Sewer Line
Your main sewer line is the one that carries all wastewater from your home out to the street. When this line gets blocked by tree roots, grease buildup, or any foreign objects flushed down the system =, every single drain in the house will be impacted.
A key sign is when the toilet gurgles as you use other fixtures or you notice that water backs up in the shower or sink shortly after flushing.
One thing we must emphasise is that you shouldn’t consider fixing this as a DIY job. Proper diagnosis usually involves a CCTV drain inspection, then followed by professional clearing.
Alternatively, the issue may relate to a blocked sewer pipe or a clogged sewer line, which requires specialised equipment to fix safely.
5. Faulty Pipe Installation or Damaged Pipes
Sometimes the issue can actually come from poorly-installed or incorrectly-sloped pipes, commonly affecting older homes (those built before the 1980s with ageing material)
Such faults can trap air and create ongoing gurgling sounds. In addition, cracked or damaged pipes can also disrupt normal flow.
The best way to deal with this pipe issue is by letting a licensed plumber to assess the system and they can recommend repair or relining.
As this plumbing issue involves the main line, you should seek expert assistance from trusted plumbers. Note that repairing the sewer line can be costly.
How to Fix a Gurgling Drain (DIY Methods)
Do you have only one drain that’s gurgling? Try out the following simple fixes before calling in a professional. *Caution: We don’t recommend chemical drain cleaners at all cost as they usually do not fix the root cause and can damage pipes in older homes.
1. Use a Plunger
Create a tight seal over the drain and plunge firmly 10–15 times.
Best for: Works well on sinks, showers, and minor blockages.
2. Pour Boiling Water
Pour hot water down the drain in 2–3 rounds and do it slowly (allow a few minutes between each pour).
Best for: Effective for grease buildup.
3. Try Baking Soda and Vinegar
First, the baking soda goes into the drain. Second, follow that with white vinegar. Let it sit for 20–30 minutes and flush with hot water.
Best for: This legendary combo is known for its effectiveness in many drain blockage issues. Although, note that this is not a long-lasting solution.
4. Use a Drain Snake
Feed the snake into the drain, rotate it to catch debris, and carefully pull it out.
Best for: Removing deeper clogs that a plunger cannot reach.
5. Flush the Vent Pipe (Only try this if Accessible)
A potential vent issue can be safely assessed if you can do it from ground level. Once you’re in, try flushing it with a hose to remove debris.
Further reading: How to Unblock Shower Drain
When to Call a Plumber
If any minor blockages go beyond all the DIY attempts, it is your cue to get a professional involved early to step in!
Call experienced plumbers like us the minute you notice any of the following strong signs:
- Gurgling in multiple drains at the same time
- Sewage smells coming from your drain
- Water backing up in the shower or bathtub when you flush the toilet
- The gurgling keeps coming back after you have cleared it
Water pooling outside near drains or in the yard
Proper diagnosis matters, which is why Neighbourhood Plumbing uses CCTV drain inspection to locate the issue accurately.
Our team is also equipped with high-pressure cleaning tools like a jet blasting service to clear blockages properly.
How to Prevent a Gurgling Drain
After every job, we’d educate our customers about how a bit of regular maintenance can go a long way in keeping your drains quiet and flowing properly.
Here’s what you can do to stay on top of drainage systems:
- Use a drain screen in sinks and showers to catch hair and debris.
- Do not pour grease or oil down the kitchen sink. Simply let it cool and dispose of it in the bin
- Pour hot water down kitchen drains weekly to help prevent buildup
- Run water in rarely used drains to help keep the P-trap full
- Book a preventative inspection if your home is older, especially in established Melbourne suburbs
Conclusion
Gurgling drains indicate a blockage in your house pipes, which is normally caused by a partially or completely clogged drain, blocked vent, troubled main sewer line, or damaged P-Trap.
If only one sink gurgles, you can quickly fix it with materials available at home, like a kettle with boiling hot water, drain cleaner, vinegar, and baking soda.
When the issue affects multiple drains or involves main pipelines that require extra attention, prioritise safety and avoid attempting to fix it yourself.
Instead, contact Neighbourhood Plumbing to discuss your plumbing needs and learn more insightful tricks to prevent the same issue from happening again.
FAQs (Frequently Asked Questions)
1. Why Is My Sink Gurgling but Not Blocked?
The noise comes from trapped air passing through a narrow path caused by delicate debris like rice, coffee grounds, and pet fur.
2. What Is Gurgling in Pipes?
Gurgling in pipes is the first sign of a blocked drain, a clogged vent system, or even a serious issue with the main sewer line.
3. How To Stop Bath Gurgling?
Using a plunger and a snake can effectively free your bathtub drain from blockages. If these methods don’t work, you might want to have plumbers check your air vent.
4. Why Does My Toilet Gurgle When I Flush but Not Clogged?
This happens when air escapes from the sewer lines. Without any significant clogs, the weird sound often calms down on its own as the air pressure gets back to normal.
5. Why Does My Sink Gurgle When I Flush?
When clogs are likely to hinder the flow of water and air in multiple areas, it is advisable to seek advice from professional plumbers.
About the Author
From unclogging the toughest drains to repairing leaking toilets, Ricky is a seasoned plumber who has brought his craftmanship to homes across Melbourne. He is passionate about sharing plumbing tips just as much as he is about fixing your plumbing issues. So, when your taps or pipes begin leaking, you know who to call.
