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Most blocked drains in South East Queensland homes come down to a short list of culprits: fats, oils and grease from the kitchen, wet wipes flushed down the toilet, hair, food scraps, foreign objects, and tree roots working their way into old pipes. Nearly all of it is preventable once you know what causes it.
This guide covers the early warning signs a drain is blocking, what actually causes blockages, what you should never put down your sink or toilet, and when a slow drain has turned into a job for a plumber. Call The Plumber Now clears blocked drains across Brisbane, Gold Coast, Logan and Ipswich, and the same rules apply whichever suburb you are in.
Warning signs your drain is blocking
A blockage rarely happens all at once. It builds up, and your drains usually give you a few warnings first. Watch for these signs.
- Slow drainage. Water pooling in the sink, shower or basin and taking longer than normal to clear is the first and most common sign.
- Gurgling sounds. A gurgle from the drain or a nearby fixture means water is struggling past a partial blockage and pulling air through the pipe.
- Bad smells. A foul or rotten smell rising from a drain usually means food, grease, hair or soap is breaking down inside the pipe.
- Water backing up. Dirty water rising into a sink, bath or toilet, or an outdoor drain overflowing, means the blockage is well advanced.
One important tell: if a single fixture is slow, it is usually a local clog. If several fixtures are slow, gurgling or backing up at the same time, or your toilet bubbles when you run the sink, that points to a blockage in your main sewer line rather than one drain. That is a plumber job.
What causes blocked drains
The main causes are consistent across Australian water utilities.
- Fats, oils and grease (FOG). Poured down the sink as a warm liquid, they cool and harden inside the pipe. Water Corporation reports FOG causes around 30% of its wastewater blockages.
- Wet wipes, including “flushable” ones. Wipes do not break down like toilet paper. They snag and combine with grease to form solid masses called fatbergs. Urban Utilities removes about 120 tonnes of wet wipes from its sewerage network every year.
- Hair. In showers and basins, hair binds with soap and grease into a mat that catches everything else.
- Food scraps. Coffee grounds, rice, pasta and vegetable peelings swell or clump and should go in the bin, not the sink.
- Foreign objects and sanitary products. Cotton buds, nappies, tampons, dental floss and toys do not dissolve and lodge in the pipe.
- Tree roots. Roots chase moisture and creep into small cracks and joints in older pipes, then grow and block the line. Utilities like SA Water report tree roots behind a large share of sewer main blockages.
What you should never put down the drain
Australian water authorities are clear on this. Only flush the three Ps: pee, poo and toilet paper. Nothing else belongs down the toilet, and the kitchen sink is not a bin either. Here is the quick reference.
| Never put down the kitchen sink | Never flush down the toilet |
|---|---|
| Cooking oil, fat and grease | Wet wipes (even “flushable” ones) |
| Food scraps and coffee grounds | Paper towel and tissues |
| Rice, pasta and flour (they swell) | Sanitary products and nappies |
| Coffee grounds and eggshells | Cotton buds and dental floss |
| Paint, plaster and cement wash | Anything that is not pee, poo or toilet paper |
The “flushable” label is the one that catches people out. Water utilities across Australia have made the same point: wipes labelled flushable still do not break down fast enough and remain a leading cause of blockages. Keep a small bin next to the toilet for them.
How to prevent blocked drains
A few simple habits stop most blockages before they start.
- Let cooking fat and oil cool and set in the pan, then scrape it into the bin. For liquid oil, pour it into an old container and bin it.
- Scrape plates into the bin before rinsing, and use a sink strainer to catch food scraps.
- Fit a drain screen in showers and basins to catch hair, and clear it regularly.
- Stick to the three Ps in the toilet and keep a bin nearby for wipes and sanitary items.
- Run hot water through the kitchen sink after washing up to help keep the pipe clear.
- If you have large trees near your pipes and a history of slow drains, get the line checked before it fails.
When to call a plumber (and why a drain camera helps)
Try a plunger or a drain screen clean-out for a single slow fixture. Skip the supermarket drain chemicals. They often do not clear the real blockage and can damage pipes and seals.
Call a plumber when the water keeps backing up, more than one fixture is affected, the blockage keeps returning, or you smell sewage. These usually mean the problem is further down the line, not at the plughole.
For a recurring or deep blockage, a drain camera inspection is the fastest way to find the cause. We send a camera down the pipe to see exactly what is there, whether it is grease, tree roots or a collapsed section, so it gets fixed properly the first time rather than guessed at. If the smell is the main issue, our article on why your drain is smelly explains the real causes.
As a guide, clearing a blocked drain typically runs $350 to $700 depending on the severity of the blockage and how easy the pipe is to access, in line with our typical plumber prices in Brisbane. Every job is different, so the best step is to get a quote.
Frequently Asked Questions
Who do I call for a blocked toilet or blocked sink?
A licensed plumber. For a blocked toilet, stop flushing so it does not overflow, then book a plumber. For a blocked sink, try a plunger first, but if it keeps returning the blockage is deeper in the pipe. See our blocked toilets and blocked sinks pages.
What is the most common cause of a blocked sink?
In the kitchen it is fats, oils and grease building up with food scraps. In the bathroom it is hair binding with soap. A sink strainer and binning your cooking fat prevents most of them.
Are flushable wipes safe to flush?
No. Australian water utilities are clear that wipes labelled flushable still do not break down like toilet paper and are a leading cause of blockages. Only flush pee, poo and toilet paper, and bin the wipes.
How do I know if it is a main sewer blockage?
If several drains are slow at once, your toilet gurgles when you use the sink, or water backs up across multiple fixtures, the blockage is likely in the main sewer line. That needs a plumber, and often a drain camera to locate it.
How much does it cost to clear a blocked drain?
It usually costs $350 to $700 depending on how bad the blockage is and how easy the pipe is to reach. The best way to know is to get a quote for your specific job.
Get your blocked drain sorted
Blocked drains only get worse and messier the longer they are left. If your drains are slow, smelly or backing up anywhere in Brisbane, Gold Coast, Logan or Ipswich, Call The Plumber Now can find the cause and clear it properly. Get a quote and we will get your drains running again.
