That hissing, running or gurgling sound coming from your toilet between flushes is usually a sign that internal tank components are worn out and need to be replaced. Catching it early is worth it. A leaking toilet can waste up to 6,000 gallons of water a month and quietly drive up your water bill.
A toilet making noise when not in use usually means water is slowly leaking from the tank into the bowl. When this happens, the toilet will start periodically refilling itself, which can sound like running water, hissing or gurgling.
The most common cause of this issue is worn-down internal components. This is a common problem that can cause significant water waste and a spike in your water bill.
The good news is that there are simple fixes to stop the leak. This guide will cover the common causes of your toilet making noise when not in use, how to diagnose the problem yourself and simple fixes versus when you should call a plumber.
It also includes expert insights from Michael Marugo, Plumbing Operations Manager at ABC Home & Commercial Services. He has both his Journeyman Plumber and Master Plumber licenses.
Why Is My Toilet Making Noise When No One Flushed It?
Marugo explains, “That is almost always an indication that there’s something going wrong inside the tank. One of the parts in the tank is allowing water out of the tank when you’re not using it, and the noise that you’ll hear is the toilet attempting to fill the tank back up again.”
According to Marugo, when you have a slow leak, you’ll hear the tank refill itself every few hours. However, with a rapid leak, you’ll hear the noise every 20 to 30 minutes.
“What you’re hearing is the fill valve inside the toilet that brings in new water when you flush is trying to make up for that leak that’s coming out of the tank going into the bowl,” Marugo explains.
When water leaks from the tank into the toilet bowl, the fill valve activates more frequently to refill the tank. The refilling process creates the noise you hear, which can sound like hissing or gurgling.
The tank water level drops
The float drops
The fill valve opens
Water refills the tank
Noise occurs
Keep reading to learn about common causes of tank leaks.
Common Noises Your Toilet May Make And What They Mean
Running Water Sound
Hearing the sound of running water coming from your toilet when it’s not in use could indicate a few issues. First, the rubber flapper at the bottom of the tank could be worn out, which damages the seal and causes water to leak.
Next, if the chain connected to the flush handle is the improper length or gets tangled, the flapper can’t fully close after each flush. Without a sealed flapper, water will continue to leak.
Lastly, there could be debris in your tank, such as mineral deposits or sediment, that prevents an airtight flapper seal.
Hissing Noise
A hissing sound indicates a failing fill valve, often due to age. It could also be caused by water pressure issues. For instance, if the water pressure is too high, it can cause the fill valve to make a hissing noise as it refills the tank.
If you have hard water, mineral buildup can impair the fill valve by restricting water flow, which causes unusual sounds.
Random Refilling (Ghost Flushing)
Plumbers refer to your toilet tank randomly refilling as “ghost flushing.” Essentially, water is slowly leaking from the tank to the bowl, which causes the tank water level to drop and trigger the fill valve. This process can repeat itself every few minutes or hours.
6 Common Reasons Your Toilet Makes Noise When Not in Use
| Problem | What It Means | Common Signs |
|---|---|---|
| Worn or Faulty Flapper | The flapper seals the tank opening after each flush. Over time, the rubber can degrade, warp or crack, allowing water to slowly leak into the bowl. | Water is constantly running, tank refills frequently, dye test shows a leak |
| Failing Fill Valve | The fill valve controls water entering the tank after flushing. When it begins to fail, it may not shut off properly or may create unusual noises. | Hissing sound, continuous water flow, tank takes longer to fill |
| Improper Float Height | The float regulates the water level inside the tank. If it’s set too high or too low, the toilet may overfill or refill repeatedly. | Random refilling, water level too high in tank, toilet runs intermittently |
| High Water Pressure | High water pressure, which is common in some Texas homes, can put extra strain on toilet components and create noise inside the tank. | Loud valve noises, vibrating or humming sounds, faster wear on internal parts |
| Mineral Buildup from Hard Water | Texas water often contains minerals like calcium and magnesium that can build up inside toilet components over time. | Hissing or whistling noises, poor sealing, fill valve performance issues |
| Cracked or Worn Tank Components | Aging plastic parts, loose fittings or small internal leaks can cause ongoing toilet noises and inconsistent performance. | Leaks inside the tank, intermittent running, loose or deteriorating parts |
How to Diagnose a Noisy Toilet at Home
“What we recommend that most folks do is, if you think there’s something going on in the toilet tank, get a little bit of food coloring and just put a few drops in the tank to turn the water in the tank, whatever color you’ve got, and then leave that toilet alone,” Marugo explains. “Don’t touch it, don’t flush it. Leave it alone for at least an hour. If you go back into that bathroom and you see colored water in the bowl, that’s a sure sign that something is letting water from the tank into the bowl.”
Step 1: Listen for the Type of Noise
Before doing anything, identify the type of noise that your toilet is making. Listen for hissing, running or refilling noises.
Step 2: Perform a Toilet Dye Test
As Marugo suggested, a dye test is a great way to identify a toilet tank leak.
Instructions:
- Add food coloring to the tank
- Wait 15 to 20 minutes
- Check the bowl for color
If color appears, there is a flapper leak.
Marugo mentions, “On occasion, you’ll even find leaks from the tank to the exterior of the bowl that can follow the bowl, and you’ll see little trails of colored water now running down the sides of the white porcelain. That’s a sure fire indication that the water in your tank is getting outside of the bowl.”
Step 3: Check Water Level in Tank
The water in your toilet tank should be about a half inch below the overflow tube, which is the tube that attaches to the rubber flapper. If it’s lower than that, you have a leak.
Step 4: Inspect Tank Components
Most tank leaks are caused by worn-down internal components. Look for a worn flapper, loose chain and damaged fill valve, which is the large tube next to the overflow tube. If any of these parts are faulty, replacing them will typically fix the leak.
How to Fix a Toilet That Makes Noise When Not in Use
If you’re handy, you may be able to fix a leaking toilet tank yourself. However, contacting a licensed plumber ensures that the job gets done correctly. A plumber follows the steps below to address the leak.
Fix 1: Replace the Flapper
Luckily, replacing the flapper is one of the easiest and most inexpensive fixes, and it often solves the problem without needing any further repairs.
Fix 2: Adjust the Float
By simply locating the float adjustment screw and slightly lowering the water level, you can keep your tank filled.
Fix 3: Replace the Fill Valve
If your toilet is making a loud hissing noise, the tank refills slowly or has an inconsistent shutoff, your fill valve is not doing its job. The good news is that replacing the fill valve is an easy fix.
Fix 4: Install a Pressure Regulator (If Needed)
If the noise is caused by high water pressure, a plumber can install a pressure regulator. High water pressure can damage plumbing fixtures and cause them to wear down faster. However, keep in mind that pressure regulators should be professionally installed.
Why Is It Important to Fix a Noisy Toilet?
According to Marugo, a leaking toilet can waste 1,000 to 6,000 gallons of water per month, or 200 to 300 gallons per day. Not only is the waste bad for the environment, but it can also spike your water bill.
While it may seem like a minor annoyance, it’s important to address toilet tank leaks to stop wasting water.
When a Noisy Toilet Means a Bigger Plumbing Problem
If the above fixes don’t stop your toilet from making noises, you should call a plumber. Here are a few warning signs that you may have a bigger plumbing problem going on:
- The toilet frequently refills
- You hear loud vibrating or hammering sounds
- Water is leaking around the base of the toilet
- Multiple toilets are making noise
Pressure problems, a leaking pipe and faulty shutoff valve could be causing a more serious issue. If that’s the case, don’t hesitate to contact a plumber.
Calling a plumber is the best option for complicated toilet issues, such as why your toilet won’t flush and it’s not clogged.
When to Call a Professional Plumber
Sometimes, DIY fixes aren’t enough. For example, if you replaced the internal components with new ones and the noise persists, you should call in a plumber. Persistent water waste and plumbing system pressure issues could also be contributing factors, and it’s best to leave more serious issues to the experts.
How to Prevent Toilet Noise Problems in the Future
As Marugo explains, “Most people aren’t going to dye test their toilets just randomly on a maintenance schedule. However, when it does start to make noise, do something about it right away. If it’s making noise when you’re not flushing it, even if it is only every four hours, it’s on its way to having bigger problems. Do something about that now, so we can get it fixed, and then we can save that water.”
To prevent your toilet from making noise in the future, replace your flapper every three to five years, and inspect your toilet’s internal components on a regular basis. If needed, install pressure regulators and address hard water issues.
Frequently Asked Questions
Why does my toilet randomly refill itself?
Is a noisy toilet an emergency?
How long should a toilet run after flushing?
Stop Toilet Noises With Expert Help
If your toilet is making noises when it’s not in use, it’s likely due to a slow tank leak. The most common and easiest solutions are replacing your flapper or fill valves. However, if the noises persist, you should call in expert help.
If your toilet continues making noise or running unexpectedly, schedule a professional plumbing inspection to identify the problem and prevent costly water waste.
