A gurgling toilet happens when trapped air is forced back through the drain line, typically caused by a partial blockage, a blocked vent pipe, or negative pressure in the plumbing system. Adelaide’s mature tree canopy, ageing clay pipework, and long dry summers make drain blockages one of the most common residential plumbing issues across the city.
Older suburbs with ageing clay and concrete pipework face the highest risk, particularly during dry spells when roots actively seek moisture. If you’re wondering why your toilet is gurgling, you’re not alone. Exceed Plumbing provides 24/7 emergency plumbing across the Adelaide metropolitan area. This guide covers why your toilet is making a gurgling noise, how to diagnose the cause, what you can safely try, and when to call a licensed plumber.
Toilet Gurgling Is More Common in Adelaide Than You’d Think
That bubbling sound from your toilet bowl isn’t just annoying. It’s your plumbing system flagging a problem. If your toilet is gurgling after a flush, Adelaide’s combination of mature trees, ageing sewer infrastructure, and long dry summers is likely behind it.
SA Water recorded a record 5,167 sewer blockages across the state in 2025, the highest number ever logged. Tree roots caused roughly 3,275 of those incidents. According to the 2021 ABS Census, 73.3% of Greater Adelaide dwellings are separate houses, most sitting on established blocks with mature vegetation growing directly above underground drain lines. Many of these homes were built in the 1950s to 1970s using clay and concrete pipes that develop cracks and joint separations over time, giving tree roots an easy entry point.
What Causes a Toilet to Gurgle?
A gurgling sound from the toilet almost always traces back to one of five issues within your drainage or venting system. Identifying which one helps you decide whether it’s a quick fix or something that needs professional attention:
- Partial blockage in the drain line. This is the most frequent cause of a toilet making gurgling noise. Excess toilet paper, wet wipes, or foreign objects restrict flow and trap air in the pipe. SA Water reported 1,667 wet wipe-related blockages in 2024, with Elizabeth North, Hackham West, and Morphett Vale among the worst affected. If you notice slow draining alongside the gurgling, a drain blockage is the most likely culprit.
- Blocked vent pipe or vent stack. Vent pipes on your roof allow air into the drainage system and release sewer gases safely. When leaves, bird nests, or debris block the vent, negative air pressure pulls air backwards through the toilet trap, causing toilet gurgling after flushing. Homes in tree-heavy suburbs like Mitcham, Stirling, and Blackwood are especially prone to vent blockages.
- Tree root intrusion into the sewer line. Adelaide’s single biggest drain problem. SA Water dealt with over 30,000 cases of tree root intrusion in 2020. Fast-growing species like eucalyptus, willows, and jacarandas penetrate cracked joints, grow inside the line, and progressively restrict flow. A CCTV drain camera inspection is the only reliable way to confirm root intrusion without excavation.
- Main sewer line obstruction. When the main line between your home and the SA Water network is partially blocked, every fixture in the house is affected. You’ll often notice toilets gurgling alongside slow sinks and showers. Foothills suburbs and homes surrounded by natural bushland experience this at higher rates.
- Faulty or deteriorating pipe joints. Homes in Prospect, Colonel Light Gardens, and Goodwood often have original clay pipes with cemented joints. After 60 to 100 years, these joints crack and allow root penetration and debris entry.
Warning Signs That Point to a Bigger Problem
A single gurgle after flushing might not be urgent. But a pattern of these signs suggests something more serious is developing in your sewer line or vent system:
Multiple Fixtures Gurgling at Once
If your toilet gurgles when you run the shower or use the kitchen sink, the blockage isn’t localised. It’s further downstream in the main sewer line, and wastewater from different fixtures is competing for restricted space. You may also notice toilets gurgling in other bathrooms at the same time.
Slow Drainage Across the House
When every drain is sluggish, the problem sits in a shared section of your sanitary drainage. This is common in homes with older pipework across suburbs like Mile End and West Lakes.
Sewage Odours or Water Level Changes
Gurgling combined with foul smells means sewer gas is entering your home through compromised trap seals. Sewer gas contains methane and hydrogen sulphide, both harmful with prolonged exposure. Water levels in the bowl that rise unusually high or drop very low between uses also signal venting faults or downstream blockages.
What to Do When Your Toilet Starts Gurgling
Not every case of toilet gurgling after flushing requires an emergency call-out. There are a few things you can safely check before picking up the phone:
- Try a plunger first. A heavy-duty flange plunger can clear minor blockages in the toilet’s trap. Push down firmly, pull up sharply, and repeat 15 to 20 times. If the gurgling stops after a few flushes, the blockage was localised.
- Stop using water temporarily. If multiple fixtures are affected, reduce water use to prevent the blockage from worsening. Running the dishwasher, washing machine, and shower simultaneously with a partial blockage can cause a sewage overflow.
- Don’t pour chemical drain cleaners down the toilet. They rarely fix the blockages that cause gurgling and can corrode older clay and PVC pipes. Mechanical solutions like plunging or professional hydrojet drain cleaning are far more effective.
- Check visible gully traps. Most Adelaide homes have outdoor gully traps. If one is overflowing or has standing water above the grate, the blockage is downstream.
- Inspect the roof vent if safe to do so. Removing debris from the vent opening can restore airflow immediately. If you’re not comfortable at height, leave it for a professional.
Why Toilet Gurgling Is More Common in Certain Adelaide Suburbs
Adelaide isn’t uniform when it comes to plumbing risk. If you’re asking why your toilet is gurgling, where you live plays a big part. Certain areas face higher rates of drain blockages due to housing age, tree species, and pipe materials:
- Eastern suburbs and foothills (Burnside, Mitcham, Stirling, Blackwood). Dense tree canopy with mature eucalyptus and jacarandas combined with original clay pipes makes these Adelaide’s worst areas for root-related blockages. SA Water confirms the eastern foothills see notably higher blockage rates than newer western suburbs.
- Inner-ring established suburbs (Norwood, Prospect, Unley, Goodwood). Homes built between the 1920s and 1960s often have clay or earthenware pipes with cemented joints that deteriorate over decades. A plumber working in these suburbs regularly encounters pipework that hasn’t been inspected since installation.
- Northern suburbs (Elizabeth North, Salisbury, Paralowie, Mawson Lakes). SA Water data identifies these suburbs among the worst for wet wipe blockages. Many properties here are Housing Trust-era homes with original plumbing infrastructure.
- Coastal suburbs (West Lakes, Henley Beach, West Beach). Salt air accelerates corrosion on metal fittings and connections. Sandy soil shifts around pipes, causing joint separation that leads to drain faults and gurgling.
How a Licensed Plumber Diagnoses and Fixes the Problem
Under the Plumbers, Gas Fitters and Electricians Act 1995, all plumbing work in South Australia must be performed by a licensed and registered plumber. Here’s what the diagnostic and repair process typically involves:
CCTV Inspection and Diagnosis
A waterproof camera is fed into the drain to reveal the exact location and nature of the blockage, whether it’s roots, debris, a collapse, or joint failure. This removes guesswork and ensures the right repair method is used.
Clearing the Blockage
For partial blockages, high-pressure water jetting clears pipe walls without damaging the pipe. For severe root masses, mechanical cutting tools are used first, followed by jetting. SA Water uses the same approach across its network.
Pipe Repair or Relining
If the camera reveals cracked or collapsed pipes, the plumber recommends either pipe relining or excavation and drain replacement. Relining inserts a resin-coated liner into the existing pipe, creating a smooth, jointless interior that resists future root intrusion.
Certificate of Compliance
According to the SA Government, plumbers must provide a plumbing certificate of compliance within seven days of completing work involving sewer or water main connections. This confirms the work meets AS/NZS 3500 standards. Always request this document.
How to Prevent Your Toilet From Gurgling
Prevention is always cheaper than repair. Once you understand why your toilet is gurgling, a few simple habits and periodic maintenance can significantly reduce the risk of it happening again:
- Only flush the three Ps. Pee, poo, and (toilet) paper. Wet wipes, even those labelled “flushable,” don’t break down and are Adelaide’s number one preventable blockage cause.
- Keep fats out of the sink. Cooking oils solidify in pipes and combine with waste to form fatbergs. In 2025, roughly 22% of Adelaide’s sewer blockages were caused by preventable fat buildup.
- Plant trees away from sewer lines. SA Water’s Tree Planting Guide recommends checking pipe locations before planting. Bottlebrush and native shrubs are safer than eucalyptus or willows.
- Schedule regular drain inspections. A CCTV inspection every two to three years gives early warning of root intrusion or joint deterioration, particularly for homes in Adelaide’s eastern suburbs.
- Upgrade ageing clay or concrete pipes. If your home has original drainage, proactive relining before failure occurs saves money and avoids emergency disruptions.
Areas We Service
Our plumbing, gas fitting, and drain clearing services cover the entire Adelaide metropolitan area, including Adelaide CBD, Norwood, Burnside, Unley, Prospect, Goodwood, Mitcham, Stirling, Blackwood, West Lakes, Henley Beach, Salisbury, Mawson Lakes, Elizabeth, Paralowie, Golden Grove, Modbury, Morphett Vale, Noarlunga, Happy Valley, Mount Barker, Colonel Light Gardens, Magill, Linden Park, and Fulham Gardens.
Still Wondering Why Your Toilet Is Gurgling? Get It Fixed Fast
If your toilet keeps gurgling and you can’t find the cause, don’t wait for a sewage backup. Call Exceed Plumbing on (08) 7948 7662 for same-day diagnosis and repair across Adelaide. Fixed upfront pricing, no hidden costs, and all work backed by our workmanship guarantee. Available 24/7, including nights, weekends, and public holidays.
Frequently Asked Questions
Can a gurgling toilet fix itself?
No. The gurgling signals a blockage or venting issue that won’t resolve on its own. The underlying problem typically worsens as debris accumulates or roots keep growing. Early diagnosis avoids more expensive repairs.
Why does my toilet gurgle when the washing machine drains?
The washing machine and toilet often share the same drain line. When a large volume of water hits a partial blockage, it displaces air that escapes through the toilet trap. This is common in older Adelaide homes where drainage layouts haven’t been updated.
Is a gurgling sound from the toilet dangerous?
It can be. Persistent gurgling often means sewer gas is entering your home through compromised trap seals. Sewer gas contains methane and hydrogen sulphide, which cause headaches and respiratory irritation with prolonged exposure.
Does a gurgling noise always mean a blocked drain?
Not always. While a drain blockage is the most common cause, gurgling can also result from a blocked vent pipe, negative air pressure, or deteriorating pipe joints. A licensed plumber can identify the exact cause using CCTV inspection.
How much does it cost to fix a gurgling noise in Adelaide?
Costs vary by cause. Simple drain clearing might range from $150 to $350, while CCTV inspection, hydrojetting, or pipe relining cost more. Always request a fixed upfront quote and confirm your plumber holds a current South Australian plumbing contractor’s licence.
Can tree roots really cause my toilet to gurgle?
Absolutely. Tree roots are the leading cause of sewer blockages in Adelaide, according to SA Water. Roots enter through cracked joints in older clay pipes, then grow until they restrict flow. Homes near mature eucalyptus and jacarandas in suburbs like Burnside and Mitcham face the highest risk.
