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If you are currently staring into your kitchen sink, hoping that the gunk that is currently clogging it will magically disappear, you are not alone. Fat, oil, and grease (FOG) are by far the leading cause of kitchen sink blockages in Sydney. Whether you are slow-cooking a Sunday roast in Penrith or running a busy cafe by the Sydney Harbour, fat poured down the drain will always congeal into a thick, greasy blockage.
At Emergency Drains, we have our team of licensed plumbers spending hundreds of hours a month unblocking thousands of blocked sinks around Sydney. In this article we will show you how to unblock a kitchen sink drain from a grease deposit, what chemicals you should never use on your sink, and when to call in the professionals.
If you are short on time, here is the safest and most reliable way to remove grease from the drain on your own:
Grease clogs kitchen sinks when hot fat, oil, and grease cool down in your plumbing. Once the fat has cooled, it will harden into a wax-like substance that traps food particles, causing your drain to completely block so that no water can pass through.
To explain how to unblock a kitchen sink drain from grease, you would need to understand how it became blocked in the first place but one of the major problems we see in Sydney is an ignorance about the nature of the problem itself.
When you dump hot bacon fat or oil down the drain, it’s liquid. But as it snakes its way down your p-trap and into the underground lines, it begins to cool. Especially if it’s a chilly winter morning in Sydney. The fat starts to congeal on the sides of your PVC or copper pipes.
With time, the layer of the solid substance will thicken, trapping coffee grounds, rice, and other particles inside it. This process reduces the pipe’s diameter and causes a local flow stagnation. As a result, the sink will start draining slower and slower until the day when it will clog completely.
The repeated use of hot water may lead to the opposite effect because the thin layer of hardened grease will resist the flow of the liquid, sliding down the pipe and eventually forming a massive blockage farther from the sink.
Understanding the type of pipes that run through your home is an essential step before you begin running any DIY down the drain. Across Sydney, there’s a diverse range of housing types, from older established terrace houses that front the Inner West to newer developments of apartment buildings that rise up from Parramatta and everything in between.
| Pipe Material | Common Sydney Locations | How Grease Affects It | Risk of DIY Chemical Cleaners |
| Copper | Older homes, Eastern Suburbs | Grease sticks moderately. Smooth interior helps flow. | Moderate: Caustic chemicals can cause pitting or accelerated corrosion over time. |
| Galvanised Steel | Pre-1970s homes, Inner West | High risk. Internal rusting creates a rough surface that traps grease easily. | High: Highly susceptible to chemical corrosion. Can cause immediate leaks if degraded. |
| PVC (Plastic) | Modern homes, Western Sydney, New Builds | Low risk. Smooth interior, but grease can still accumulate at joints and bends. | High: Chemical cleaners generate intense exothermic heat that can literally melt or warp thin PVC pipes. |
Avoid using supermarket drain cleaners for a sink that is clogged with grease. These typically involve an exothermic (heat-producing) chemical reaction which can dissolve the organic material in the pipe. In a sink with a fat blockage, this could mean a thin layer of the chemical on top of the fat blockage, which could be sufficient to melt the plastic pipes or destroy the seals on your P-trap.
Not all clogs are the same. Before trying to do a pipe-safe drain cleaning, look out for these warning signs to know whether it is a good idea to call an emergency plumber in Sydney or if you can manage it on your own.
| DIY Appropriate (Minor Blockage) | Call a Plumber (Serious Blockage) |
| Water drains, but very slowly. | Sink is completely full and won’t drain overnight. |
| The blockage is isolated to the kitchen sink. | Multiple drains (e.g., laundry and kitchen) are backing up. |
| Mild, stale food odour. | Strong sewage smell coming from the drain. |
| Gurgling noises only when the sink is draining. | Gurgling noises in the sink when you flush the toilet. |
If you are experiencing the symptoms on the right, the blockage has likely moved past your kitchen plumbing and into your main wastewater pipe.
If you have a localised kitchen sink drain blockage, here is how our plumbers recommend tackling it using household items.
This is the simplest solution for new or slight blockages. The dishwashing liquid will attack the fat molecules, whilst the boiling water will help to dissolve them, letting them run off down the drain with ease.
Why does dishwashing liquid work?
It contains surfactants, which are molecules with a hydrophilic tail and a lipophilic head. They interact with the grease, surrounding it and breaking it into small pieces, which are then flushed away with water.
Baking soda + vinegar unclog drains due to the formation of carbon dioxide gas bubbles that occur when the two are mixed together. This gas exerts a large force on any grease blockage, causing it to disperse in the confined space within the pipe
People sometimes think that this process works by melting the blockage but it actually does not.
The baking soda is basic and the vinegar is acidic so they do not actually melt the grease blockage; instead, they form expanding gas bubbles that cause pressure on the blockage within the drain.
A plunger works by creating a vacuum and hydrostatic pressure that allow it to pull and push a plug of grease until it breaks.
| DIY Method | Safe for Pipes? | Works for Grease? | Success Rate |
| Dishwashing Liquid + Boiling Water | Yes | Highly Effective | 75% |
| Baking Soda + Vinegar | Yes | Moderately Effective | 60% |
| Cup Plunger | Yes | Effective | 80% |
| Chemical Drain Cleaners | No | Poor (Often makes it worse) | 20% |
If the above suggestions do not work, then you have a fatberg, which is firmly lodged in your drains. You must not try to fish it out with a wire coat hanger, since this can cause cracks to form in the PVC pipes. It is now time to research professional kitchen drain cleaning.
If the methods above don’t work, and you’re still experiencing a blocked drain in your kitchen sink, you’ll need to call in the professionals. The grease could well have turned to fat, or tree roots could have invaded your main sewer, entangling the fat blocking your pipes.
With emergency drains we use a high-tech approach to removing the fat from your drains so that we’re not just drilling holes into the fat; we’re unclogging the walls of the pipe itself.
Before we turn on the hose and start flushing, we want to see the obstruction. Our plumbers can do that by inserting a high-definition video into your line to see exactly where the buildup of grease is, how long it is, and if the pipe itself is cracked or broken.
For a grease-blocked sink, using a traditional drain snake (electric eel) is a lost cause. The snake will simply push through the soft plug of congealed grease, creating an even tinier hole that will instantly collapse back in on itself when the pressure is released.
Instead, we use hydro-jetting. High-pressure water, going up to 3,000 psi, is forced through a special nozzle. The backwards-facing water jets on the nozzle push the hose into the pipe while scouring the walls clean. The high pressure pushes through even the hardest FOG deposits like a hot knife through butter, leaving the pipes clean and shiny.
Want to know more about what warrants a call to our team? Read our comprehensive guide on DIY vs Professional: When to Call a Plumber for Blocked Drains.
Prevention is always better (and cheaper) than cure. According to Sydney Water, millions of dollars are being spent every year fixing up Sydney’s wastewater systems that were damaged by fat, oil and grease (FOG) running down drains from both homes and businesses.
So here’s our plumber-approved checklist to avoid the worry and expense of blocked drains:
Dealing with a blocked kitchen sink in Sydney can be an infuriating inconvenience, but there are ways to address the issue without causing a major disruption to your day.
If the blockage is recent, attempting to use dishwashing liquid and boiling water or baking soda and vinegar are great drain cleaners that can solve the issue safely and from home, without damaging the pipes in the process.
However, if you find yourself plunging the sink over and over again, if the water simply refuses to drain despite your best efforts, and if you detect the unwelcoming odour of something rotten in there, it is time to call in professionals. In such cases, DIY methods will not work, while store-bought chemicals will only destroy the pipes beyond repair, requiring expensive excavations later on.
Don’t let a blockage in your sink make your day bad all day. Our licensed local plumbers are waiting to help you. We provide emergency plumbing services all over the Sydney basin, Northern Beaches, and Greater West regions.
With modern CCTV and hydro jetting technology, we are able to clear your pipes in record time. Give us a call now to set up your quick, reliable and, most importantly, guaranteed pipe clearing service.
Can Coca-Cola unblock a grease-clogged sink?
While Coca-Cola includes phosphoric acid, which may partially dissolve light limescale, it is largely ineffective against a thick grease blockage. Moreover, the sugar in Coca-Cola may leave a residue that can contribute to further buildup in the pipes. It is better to use hot water and detergent.
Will boiling water damage my PVC pipes?
The standard PVC used for plumbing in Australian homes is rated for the average hot water temperature seen in households (up to 50-60°C), so you can safely run a single kettle of boiling water (100°C) through the system, but doing this regularly with large volumes of extremely hot water will irreversibly damage the plastic piping.
Why does my sink drain gurgle after the water goes down?
A gurgling sink implies that there is air in the lines that is attempting to escape the system. It is an indication that there is an obstruction ahead, which is preventing gas from exiting through the vent. This may suggest that a blockage is forming, and it should be cleared soon.
Is bleach good for clearing a blocked sink?
No. Bleach is a disinfectant, not an unblocker. It will disinfect the water in your sink, but it will do nothing for the fats, oils or grease that are causing the blockage. Trust me, we plumbers don’t want to be sent to deal with a basin full of bleach water. We can manage a clogged drain; we can manage a basin full of dirty water, but a basin full of bleach water is something we really don’t want to have to handle.
How long does it take for a plumber to unblock a kitchen sink?
If you call us, Emergency Drains, for our blocked drain services, we assure you that the most common kitchen sink blockages are cleared within 45-60 minutes using hydro jetting. In turn, if the blockage is situated deeper in the main drain, it would take 1-2 hours to clear along with having a drain inspection using a drain camera.
