7 Signs You Have a Blocked Drain
The clearest signs of a blocked drain are water draining slowly, gurgling noises, bad smells, and water pooling or overflowing where it shouldn't. Catch these early and a blockage is usually a quick, cheap fix. Ignore them and you risk sewage backing up into your home. Here are the seven signs worth watching for, and what each one is telling you.
Blocked drains rarely happen overnight. They build up gradually as debris collects in the pipe, which is why the early signs are so easy to miss or explain away. The good news is that the sooner you recognise them, the simpler and cheaper the fix. Once a blockage becomes a full backup, it's messier, more disruptive and more expensive to sort out.
1. Water drains slowly
This is the most common early warning. If your sink, shower or bath is taking longer than usual to empty, something is building up in the pipe — hair, soap scum, grease or food scraps. One slow drain usually means a local blockage. If several fixtures are slow at once, the problem is likely deeper in your main drain line.
2. Gurgling sounds
Hear a gurgle from the plughole or toilet after you run water or flush? That's air trapped by a partial blockage being forced back up the pipe. It's an easy sign to dismiss, but gurgling almost always gets worse, not better. Treat it as a nudge to act before the drain stops entirely.
3. Bad smells
A foul, rotten or sewage-like smell around a drain, sink or outside the house often means waste is sitting in the pipe instead of flowing away. Trapped food, grease and organic matter break down and the odour drifts back up. If cleaning the plughole doesn't shift it, the smell is coming from further down.
4. Water pooling or backing up
Water rising in the shower base while you run the basin, or coming up in one fixture when you use another, is a strong sign of a shared blockage downstream. When wastewater has nowhere to go, it finds the lowest open outlet — which is why a blocked main can show up as water surfacing in an unexpected spot.
5. A toilet that won't flush properly
If your toilet is slow to clear, rises alarmingly before draining, or bubbles when you flush, the blockage may be in the toilet trap or the main sewer line. A toilet backing up is one to take seriously — it's the fixture most likely to cause a messy, unhygienic overflow inside the home.
6. Overflowing drains or gully traps
An outdoor gully or drain overflowing — especially with dark, smelly water — usually means the main line is badly blocked and wastewater is escaping at the first available point. This is often the last warning before an indoor backup, so it's worth calling a plumber promptly. Our blocked drains service can clear it before it reaches your floors.
7. Recurring blockages in the same spot
If the same drain keeps blocking despite your best efforts, something structural is usually going on — a partial collapse, a build-up of scale, or tree roots growing into the pipe. A quick plunge only clears the symptom. A CCTV drain inspection shows exactly what's causing it so it can be fixed for good.
Should you worry about a single slow drain?
Not necessarily — but don't dismiss it either. A single slow drain in one basin or shower is usually a local build-up you can often clear yourself, and it's a good prompt to give that drain some attention before it worsens. What matters more is the pattern. If several fixtures slow down together, if the toilet is involved, or if you notice smells and gurgling alongside the slow drainage, the problem is likely deeper in the main line and needs a professional look. The distinction between a one-off nuisance and a warning of something bigger is really about how many signs are showing up at once.
What causes blocked drains?
Most household blockages come down to a handful of culprits:
- Hair and soap scum in showers and basins
- Fat, oil and grease poured down the kitchen sink, which cools and hardens
- Food scraps and coffee grounds
- Wet wipes and sanitary items — even "flushable" wipes don't break down like toilet paper
- Tree roots seeking moisture in older or cracked pipes
- Foreign objects — toys, cotton buds, dental floss
Can you clear a blocked drain yourself?
Sometimes. A plunger or a bit of hot water and dish soap can shift a minor kitchen or basin blockage. A drain snake can reach a little further. But avoid chemical drain cleaners — they can damage pipes, are dangerous to handle, and often just push the problem along. If the blockage keeps coming back, affects more than one fixture, or involves the toilet or main line, it's time for a professional with the right tools like a drain camera and hydro jetter.
The advantage a licensed plumber brings isn't just muscle — it's diagnosis. A hydro jetter uses high-pressure water to scour the pipe walls clean rather than just poking a hole through the blockage, so it's far less likely to return. Paired with a CCTV camera, the plumber can see exactly what caused the problem and whether the pipe itself needs attention. That turns a recurring headache into a one-time fix.
When to call a plumber
Call a licensed plumber if you notice multiple slow drains at once, sewage smells or backups, an overflowing outside gully, or a blockage that returns no matter what you do. These point to a problem in the main line that needs proper diagnosis. Learning how to prevent blocked drains will also save you a lot of hassle down the track.
Got a drain that's slow, smelly or backing up? Call our licensed Canning Vale plumbers and we'll clear it properly.
Frequently asked questions
What is the first sign of a blocked drain?
Usually water draining more slowly than normal. A slow sink, shower or bath means something is building up in the pipe. Catching it at this stage means a quick, cheap fix before the blockage becomes a full backup.
Why does my drain gurgle?
Gurgling is air trapped by a partial blockage being pushed back up the pipe. It's an early warning that the drain is starting to clog. It rarely fixes itself, so it's worth acting before the drain stops flowing altogether.
Are chemical drain cleaners safe to use?
We don't recommend them. Harsh chemical cleaners can corrode pipes, are hazardous to handle, and often just shift the blockage rather than remove it. A plunger, hot soapy water or a professional clear-out is safer and more effective.
Why does the same drain keep blocking?
A recurring blockage in one spot usually points to a structural cause — scale build-up, a partial pipe collapse or tree roots growing in. A CCTV drain inspection reveals the real problem so it can be fixed permanently rather than repeatedly cleared.