What to Do If Your Toilet Keeps Running (and Why It Matters)
If you’ve ever walked past your bathroom and heard the sound of water running—long after the last flush—you’re not alone. A running toilet might seem like a small annoyance, but it can quietly waste hundreds of litres of water a day and inflate your water bill before you even notice. The good news? Most causes are simple to spot, and in many cases, easy to fix.
In this guide, you’ll learn:
- Why your toilet keeps running (and why it matters)
- How to troubleshoot a running toilet step-by-step
- When it’s time to call a licensed plumber
- Conclusion – Don’t Let a Running Toilet Drain Your Wallet
Let’s start by looking at what causes a toilet to run constantly—and why it’s worth fixing right away.
Why Your Toilet Keeps Running (And Why It Matters)
A running toilet might not seem urgent at first glance—but left unchecked, it can quietly drain your wallet, waste hundreds of litres of water, and lead to long-term plumbing issues. Whether you’ve just noticed the sound or your toilet has been refilling nonstop for days, understanding the cause is the first step to stopping the problem for good.
Common Causes of a Constantly Running Toilet
There are a few usual suspects when it comes to a toilet that won’t stop running. Here’s what could be going wrong inside the tank:
1. Faulty Flapper Not Sealing
This is the most common culprit. The flapper is a rubber valve that lifts when you flush and seals the tank afterward. Over time, it can wear out, warp, or become misaligned, allowing water to leak slowly into the bowl. If your toilet seems to flush itself or you hear a trickling sound every few minutes, a dodgy flapper is likely to blame.
2. Stuck or Misaligned Float
The float controls how much water fills the tank after a flush. If it’s set too high or gets stuck, the tank may overfill and trigger the overflow tube—causing a constant cycle of refilling. Think of it like trying to fill a cup that’s already full—water just keeps spilling over.
3. Toilet Valve or Flush Lever Issues
Sometimes the problem is mechanical. If the flush lever or the chain that connects to the flapper gets caught or tangled, the flapper won’t close properly. This is a simple fix but easy to overlook.
4. Faulty Fill Valve
The fill valve regulates water flow into the tank. If it’s cracked, clogged, or simply worn out (especially in older toilets), it may never shut off completely. This slow, continuous refill is a common reason your toilet keeps running even when it looks fine on the surface.
Real-World Consequences of Ignoring the Issue
High Water Bills
One of the first signs of a running toilet is an unexpected spike in your water bill. We’ve seen Sydney homeowners pay an extra $100–$200 a quarter—without realizing the culprit was a silently leaking toilet. Sydney Water’s leak detection guide offers helpful tips for identifying hidden leaks and stopping the waste.
Water Waste and Environmental Impact
A constantly running toilet can waste up to 750–1,000 litres of water per day. That’s more than the average person uses in a week. For eco-conscious households and businesses, this isn’t just a plumbing issue—it’s a sustainability one, especially when you’re trying to implement eco-friendly bathroom upgrades.
Risk of Mould or Water Damage
If leaks extend beyond the tank or go unnoticed behind the wall, they can lead to moisture buildup, mould growth, and even structural damage. What starts as a small flapper issue can turn into warped flooring or damaged cabinetry if ignored. Bathroom mold remediation becomes essential if moisture goes unchecked. For more on health concerns, see this NSW Health guide to mould, which outlines the risks and steps to prevent mould-related health issues.
Persistent Noise or Disturbance
Even if it’s not causing a flood, a running toilet can be a constant source of low-level stress. The trickling sound at night or during quiet moments can wear on your nerves—and is often the final straw that gets someone to call a plumber.
Key takeaway: A toilet that keeps running is more than a minor annoyance—it’s a warning sign. Understanding the root cause can help you stop the issue early, save water, lower your bills, and protect your home or property from bigger problems down the line.
How to Troubleshoot a Running Toilet (Step-by-Step)
If your toilet won’t stop running, don’t worry—you don’t need to be a plumber to handle the basics. Most running toilet issues can be fixed with a few simple checks and adjustments. Here’s a step-by-step guide to help you diagnose and potentially fix the problem yourself, no special tools required.
Step 1 – Shut Off the Water Supply
Before you do anything inside the toilet tank, turn off the water. This prevents accidental overflow and gives you a dry workspace.
- Locate the shut-off valve—usually a small silver knob or lever near the base of the toilet.
- Turn it clockwise until it stops. You’ll hear the flow of water stop.
Tip: If you’re a visual learner, a simple diagram showing the valve location can be helpful—especially for first-timers.
Step 2 – Check the Flapper and Chain
Once the tank is open, the flapper is the rubber seal covering the flush valve at the bottom of the tank. It’s connected to the flush handle by a chain.
- Look for signs of wear: If the flapper is brittle, warped, or not sealing properly, it’s likely the reason your toilet keeps running.
- Check the chain: If it’s too short, the flapper may not close all the way. If it’s too long, it could get caught underneath the flapper.
Quick fix: Replace the flapper if it looks damaged—they’re inexpensive and easy to install.
Step 3 – Inspect the Fill Valve and Float
Next, check the fill valve—the tall vertical assembly on one side of the tank—and the float mechanism, which rises and falls with the water level.
- Float too high? The tank may overfill and spill into the overflow tube, causing a continuous refill cycle.
- Float stuck? Jiggle it gently to see if it’s caught on something.
- Fill valve hissing? That’s a sign it may not be shutting off properly.
You can adjust the float height using the screw or clip on the fill valve. If adjusting doesn’t help, replacing the fill valve may be your best bet—another affordable DIY repair.
Step 4 – Do a Dye Test for Silent Leaks
Not all running toilets make noise. If your toilet looks fine but your water bill says otherwise, try this quick test:
- Add a few drops of food coloring into the toilet tank (not the bowl).
- Wait 10–15 minutes without flushing.
- Check the bowl—if the color appears, you’ve got a silent leak.
This usually means the flapper isn’t sealing properly or there’s a slow leak around the flush valve.
Key takeaway: Many toilet issues are easy to diagnose and fix on your own. From replacing a worn flapper to adjusting a float, these small DIY toilet fixes can save water, money, and frustration. And if the problem persists? Don’t worry—there’s always expert help nearby.
When to Call a Licensed Plumber
While many running toilet issues can be handled with a quick DIY fix, there are times when calling in a professional is the safest—and smartest—move. Knowing when to stop tinkering and trust an expert can save you time, money, and avoid turning a small problem into a bigger one.
You’ve Tried Fixes But the Toilet Still Runs
If you’ve replaced the flapper, adjusted the float, and run the dye test—but your toilet just keeps running—it’s time to bring in a licensed plumber. Persistent issues often point to deeper mechanical problems inside the tank or even hidden leaks in the bathroom plumbing that aren’t visible to the naked eye.
Water Leaks Around the Base or Behind the Wall
A running toilet that causes water to pool at the base or leak behind the wall can signal a more serious fault, like a damaged wax seal or a hidden pipe issue. These problems can lead to mould, rot, and structural damage if not addressed quickly.
In these cases, DIY can only go so far. Professional tools and know-how are needed to safely diagnose and repair the problem without damaging your floors or walls.
You’re Not Confident Handling Repairs Safely
There’s no shame in feeling unsure—especially when it comes to water systems in your home or business. If the idea of removing parts, shutting off valves, or dealing with water leaks feels overwhelming, it’s better to call a licensed plumber than risk making it worse.
A quick visit from a professional can save hours of stress and prevent unnecessary costs down the road.
You Want a Long-Term or Eco-Friendly Upgrade
Sometimes it’s not about fixing what’s broken—it’s about upgrading for better performance and sustainability. If your toilet is over 10 years old, constantly acting up, or you’re interested in reducing water usage, a plumber can help you choose and install a high-efficiency toilet.
This not only improves reliability but also helps the environment and can lower your water bill for years to come.
Still can’t stop that running toilet? We’re just a call away—serving all of Sydney, 24/7. Whether it’s a quick repair or a long-term upgrade, In House Plumbing is here to help—on time, every time.
Conclusion – Don’t Let a Running Toilet Drain Your Wallet
A running toilet might seem like a small inconvenience, but it can lead to big problems if ignored—higher water bills, wasted resources, and even hidden damage to your home. The good news? Most causes are simple to diagnose and fix yourself, from adjusting a float to replacing a worn-out flapper.
If you’ve followed the steps in this guide and your toilet still won’t stop running, or if you’re just not comfortable handling the repair, you’re not alone. At In House Plumbing, we’ve helped hundreds of Sydney homeowners and business owners stop silent leaks, reduce water waste, and restore peace of mind—quickly and cleanly.
Every drop counts. Fixing a running toilet not only protects your property—it supports smarter water use in your home or business.Need a second opinion or fast fix? Get in touch today. We’re here 24/7, ready to help with honest advice and expert service you can count on.
Frequently Asked Questions (FAQs)
A toilet that runs continuously is usually caused by a faulty flapper, a misaligned float, or a fill valve that won’t shut off properly. These parts control the water flow inside the tank—when one isn’t working, water keeps cycling through. Silent leaks can also cause the tank to refill regularly, even if you don’t hear it.
Yes, in many cases you can fix a running toilet yourself. Simple issues like adjusting the float, replacing the flapper, or checking the chain are common DIY fixes. But if you’ve tried those and the toilet still runs—or if you’re seeing leaks around the base—it’s best to call a licensed plumber to avoid bigger problems.
A constantly running toilet can waste anywhere from 750 to 1,000 litres of water per day—that’s enough to fill a small backyard pool in just a week. Over time, this adds up to a serious environmental impact and a noticeable increase on your water bill.
Start by checking the flapper inside the tank—it’s often the simplest and most common fix. If it’s not sealing properly, replacing it usually solves the problem. You can also check the float and fill valve for easy adjustments. Don’t forget to shut off the water supply before you start.
While it might not seem urgent, a running toilet can lead to expensive consequences if ignored. Beyond the noise, it can cause water damage, encourage mould growth, and significantly raise your water bills. It’s more than just annoying—it’s a problem worth fixing early.
