Blocked Toilet: Causes & How to Fix It
A blocked toilet is one of the most common plumbing problems, and the good news is that many blockages can be cleared yourself with a bit of patience and the right technique. Before you reach for the phone, a plunger and a few simple steps will often do the job.
Here's what causes blocked toilets, how to clear one safely, what you should never flush, and the point at which it's time to call a licensed plumber.
What causes a blocked toilet?
Most toilet blockages come down to something going down that shouldn't. The usual culprits are:
- Too much toilet paper flushed at once, especially thick or multi-ply
- Wet wipes, including so-called "flushable" ones, which don't break down like toilet paper
- Sanitary products, nappies and cotton buds, which swell and snag
- Kids' toys or other objects dropped in and flushed
- A partial blockage further down the drain, sometimes caused by tree roots in older pipes
If your toilet keeps blocking despite careful use, the problem may be deeper in the drain rather than in the pan. That's when it points to a wider issue covered in our blocked drains service.
Before you start: stop the overflow
If the bowl is full and rising, don't flush again, as that just adds more water. If it looks like it might overflow, take the lid off the cistern and push the flapper valve down by hand to stop water refilling, or turn off the isolation tap behind the toilet. Let the water level settle before you start.
How to clear a blocked toilet
Method 1: The plunger
A proper toilet plunger (the flanged kind that fits into the outlet) is your best first tool.
- Make sure there's enough water in the bowl to cover the plunger head, adding some if needed
- Position the plunger over the outlet hole and press down to form a seal
- Push and pull firmly and steadily, keeping the seal, for 15 to 20 pushes
- Pull the plunger away sharply on the last pull to break the blockage free
- Repeat if needed, then test with a flush once the water drains
Method 2: Hot water and detergent
For a soft blockage, pour a good squirt of dishwashing liquid into the bowl, followed by a bucket of hot (not boiling) water from about waist height. Let it sit for 20 to 30 minutes. The detergent helps lubricate and the warm water can soften the blockage enough to flush through. Never use boiling water, as it can crack the porcelain.
Method 3: A toilet auger
If plunging fails, a toilet auger (closet auger) is a flexible cable you feed into the outlet to reach and break up a blockage further along. Wind it in gently until you feel the obstruction, then work it through. Take care, as forcing it can scratch the pan.
What not to do
- Don't use harsh chemical drain cleaners in the toilet. They're often ineffective on toilet blockages and can damage pipes and seals, and they make it hazardous for a plumber to work on later.
- Don't keep flushing a blocked toilet, as you'll flood the floor.
- Don't use boiling water, which risks cracking the bowl.
What you should never flush
| Item | Why it causes blockages |
|---|---|
| Wet wipes (even "flushable") | Don't break down, snag and build up in the pipe |
| Sanitary products and nappies | Absorb water and swell dramatically |
| Cotton buds and dental floss | Tangle together and catch other debris |
| Paper towel and tissues | Much stronger than toilet paper, doesn't disintegrate |
| Fats, oils and food scraps | Congeal and stick to pipe walls |
The rule of thumb is simple: only the three Ps go down the toilet, meaning pee, poo and (toilet) paper. Everything else goes in the bin.
When to call a plumber
Call a licensed plumber if:
- Plunging and augering haven't cleared it after a few attempts
- Multiple drains are slow or backing up, not just the toilet, which suggests a main drain blockage
- Water or sewage is coming up through other fixtures, like the shower or floor waste
- The toilet blocks repeatedly, which can indicate tree roots or a pipe fault
These signs point to a blockage deeper in the system that DIY tools can't reach. A plumber can use a camera to find the cause and clear it properly. Recurring blockages in older suburbs are often tree roots, which we cover in our guide on the signs of a blocked drain.
Why does my toilet block repeatedly?
A one-off blockage is usually just something that shouldn't have gone down the pan. But when the same toilet blocks again and again, the cause is almost always further down the line, and no amount of plunging will fix it for good. Common reasons include:
- A build-up of non-flushables like wet wipes that have accumulated and narrowed the pipe over months.
- Tree roots growing into the sewer line through cracks in older clay pipes, common in established Perth suburbs. Roots snag paper and waste flowing past, so the toilet blocks over and over.
- A partially collapsed or bellied pipe where waste pools instead of flowing away.
- An older low-flow toilet that doesn't move waste far enough down the drain, letting build-up form just past the pan.
Any of these needs proper diagnosis rather than repeated DIY attempts. A drain camera shows exactly what's going on, so the fix targets the real cause instead of the symptom.
Keeping your toilet trouble-free
Prevention is easier than cure. Stick to the three Ps, keep a bin in the bathroom so wipes and sanitary items never get flushed, and go easy on the toilet paper if your system is prone to blocking. If you're in an older home with a history of root problems, a periodic drain check keeps small issues from becoming a sewage back-up. A little care goes a long way to avoiding the mess and inconvenience of a blocked toilet.
Toilet still blocked after all that? Call our licensed Canning Vale plumbers to clear it fast and check there's nothing bigger going on in your drains.
Frequently asked questions
Why does my toilet keep getting blocked?
Repeated blockages usually mean the problem is deeper than the pan, such as a partial blockage in the drain, a build-up of non-flushables, or tree roots in older clay pipes. A plumber with a drain camera can pinpoint the cause.
Can I use drain cleaner to unblock a toilet?
It's best avoided. Chemical drain cleaners are often ineffective on toilet blockages, can damage pipes and seals, and make it hazardous for a plumber to work on the toilet afterwards. Stick to a plunger, an auger, or hot water and detergent.
Are flushable wipes actually safe to flush?
No. Despite the label, so-called flushable wipes don't break down like toilet paper and are a leading cause of toilet and drain blockages. Put all wipes in the bin, not the toilet.
How do I stop my toilet overflowing when it's blocked?
Don't flush again. Remove the cistern lid and push the flapper valve down by hand to stop water refilling, or turn off the isolation tap behind the toilet. Let the water level drop before attempting to clear the blockage.