The short answer
To unblock a drain, start with a plunger, sealing the overflow first. If that doesn't clear it, remove and clean the trap under the sink or the grate in the shower, then try a drain snake. If more than one fixture is blocked, or the gully outside is overflowing, the blockage is in the main line and needs a plumber.
We've been clearing blocked drains across Melbourne's northern suburbs since 2012, and we quote the job free with no call-out fee.
Blocked drains have a sense of timing. The kitchen sink waits until there’s a roast tray soaking in it. The shower waits until you’ve got shampoo in your eyes. The toilet waits for guests.
Plenty of blockages can be cleared at home. Some can’t, and the last section covers how to tell which one you’ve got.
| Where it’s blocked | Usual cause | Try first |
|---|---|---|
| Kitchen sink | Fat, grease and food scraps | Hot tap water, then a plunger, then the trap |
| Bathroom basin | Hair and soap | Clean the pop-up plug and the trap |
| Shower | Hair | Lift the grate and pull the hair out |
| Toilet | Too much paper, or something that isn’t paper | A toilet plunger |
| Several fixtures at once | A blockage in the main sewer line | Stop and call a plumber |
| Gully outside overflowing | A blockage in the main sewer line | Stop and call a plumber |
First, is it one drain or several?
Check this before anything else. If one sink or one shower is slow and everything else drains normally, the blockage is close to that fixture, and it’s usually something you can reach.
If the toilet gurgles when you run the bath, or two or three fixtures are slow at once, the blockage is further down, in the pipe they all share. No plunger reaches that far. Skip straight to the last section.
How to use a plunger properly
A plunger works by pushing and pulling water through the pipe, and it only works if the air can’t escape. So seal the gaps first.
- Block the overflow. Most basins and sinks have an overflow hole near the rim. Cover it with a wet cloth, or the plunger just pushes air out of it.
- Get some water in. Leave enough water in the basin or sink to cover the plunger’s cup.
- Seal and pump. Press the cup flat over the plughole and pump firmly up and down ten or fifteen times, keeping the seal.
- Pull away sharply. The pull often does more than the push.
A double sink needs the other plughole blocked with the plug or a cloth, or you’ll just move the water from one side to the other. For a toilet, use a proper toilet plunger with a flange that fits into the outlet, not a flat sink plunger.
Clean the trap or the shower grate
If plunging doesn’t clear it, the blockage is often sitting in the trap. That’s the curved or cup-shaped section of pipe directly under a sink or basin, and it’s there to hold water so sewer smells can’t come back up.
Put a bucket underneath first. Most modern traps unscrew by hand, and older ones may need a wrench. Tip out what’s inside, rinse it, check the seals are sitting properly, and screw it back on firmly. Run water and check for drips before you pack the cupboard back up.
In a shower, lift out the grate and pull out what’s under it. It’ll be hair. It’s always hair. A cheap plastic drain claw from the hardware store reaches further than fingers and is much nicer to use.
Using a drain snake
A drain snake, also called a drain auger, is a flexible steel cable you feed into the pipe to break up or hook out a blockage. A hand-held one is cheap and reaches a few metres, which covers most sink and shower blockages past the trap.
Feed it in gently, turning the handle as you go. When you feel resistance, turn and push a little to break it up or hook it, then pull it back out slowly. Expect whatever comes out with it to be unpleasant.
Stop if the snake keeps hitting something hard in the same spot. That can be a joint, a bend or a damaged section of pipe, and forcing a cable against it can make it worse.
What not to pour down a drain
- Boiling water in a toilet or plastic pipe. It can crack porcelain and soften pipe joints. Hot tap water is fine.
- Chemical drain cleaners. They're caustic, they can damage older pipes, and if they don't work you're left with a blocked drain full of chemical.
- Fat and oil, even hot. It sets further down the pipe. Wipe pans out and bin the scrapings.
- Wet wipes, including the "flushable" ones. They don't break down like toilet paper does.
Bicarb soda and vinegar is the one everyone tries. It fizzes impressively and does very little to a real blockage. It’s fine for freshening a drain that smells, and that’s about it.
When to stop and call a plumber
There’s a point where more effort at the sink just moves the problem around. These are the signs you’ve reached it.
| Sign | What it usually means |
|---|---|
| More than one fixture is blocked | The blockage is in the shared line |
| The gully outside is overflowing | The main sewer line is blocked |
| Water comes up in the shower when you flush | The main sewer line is blocked |
| It clears, then blocks again within weeks | Tree roots or a damaged pipe |
| The snake hits something hard every time | A broken, sagging or displaced section of pipe |
That gully outside is worth knowing about. It’s called an overflow relief gully, and it’s designed to overflow in the yard when the sewer line is blocked, so sewage doesn’t come up through the shower first. If it’s overflowing, stop using water in the house and call.
A drain that keeps blocking is usually tree roots in an old clay line, or a section of pipe that’s cracked or dropped. Clearing it again gets the water moving, but a CCTV drain inspection shows what’s actually causing it, so the next fix is the last one. If you’d like to know what that costs first, our guide to what a CCTV drain inspection costs has the numbers.
For a blocked main line, our blocked drain clearing page covers what we do and how. What a blocked drain usually costs to clear is in our guide to what a plumber costs in Melbourne. Our phone’s answered 24 hours a day, which matters most when it’s the toilet.
Read this next: What does a CCTV drain inspection cost?