A toilet that randomly runs for a few seconds by itself is experiencing a phantom flush. Phantom flushes are toilet runs that happen suddenly and seemingly at random. Luckily, it’s easy to identify and fix this problem even without the need for a plumber.
Your toilet randomly running for a few seconds is a phantom flush which is caused by water leaking from the toilet tank to the toilet bowl due to a damaged flapper, sediment buildup on the flapper and others. Clean or replace the flapper to fix the issue.
Phantom or ghost flushes increase your water bill since water runs from the toilet tank to the sewer for no reason. A single flush of the toilet uses about 1½ gallons of water with steady toilet leaks wasting as much as 200 gallons of water a day. As such, the sooner you fix a toilet that runs sometimes on its own, the better for your water bills.
Causes and fixes for a toilet that runs randomly
| Causes of a running toilet | Fixes |
| Faulty toilet flapper | Replace the flapper valve |
| Sediment buildup in the flapper | Clean the toilet flapper |
| Water leaking into the overflow tube | Replace the float ball |
| Faulty flapper chain | Fix or replace the flapper chain |
| Faulty fill valve | Replace the fill valve |
| Faulty flush valve assembly | Replace or fix the flush valve |
| Faulty flush control mechanism | Replace or fix the flush valve |
| Faulty toilet handle | Fix or replace the handle |
| Sensor malfunction | Recalibrate or replace the sensor |
| Wrong water level | Adjust the water level in the tank |
| Leaky seals | Replace cracked gaskets |
What makes a toilet run by itself?
Some of the causes behind a toilet that runs occasionally include the following:
Faulty toilet flapper
A faulty toilet flapper is one of the most common causes behind a toilet that runs occasionally. Toilets work by creating a seal between the water in the tank and the bowl so they do not leak or spill. The seal is created when the flapper closes after every flush.
When this seal becomes faulty or cracked, it can cause some water to trickle down into the bowl, which you might see as your toilet running intermittently. Faulty flappers are easy to spot since they generally do not sit evenly against the seat rim.
Sediment buildup on the flapper
When the rubber on the flapper is old, it can get stiff and allow sediments to get stuck on it. Sediments stick to anything including rubber flappers inside toilets. They then cause the flapper to stick open while the toilet isn’t in use.
If this happens, you’ll hear a noisy flush every few minutes as the tank refills. Sediment buildup also causes slow leaks that you might not notice for days or weeks because of how slowly water seeps out.
Water leaking into the overflow tube
Water leaking into the overflow tube means that it’ll leave the toilet tank. When a tank loses enough water (due to leakage or evaporation), it triggers an automatic refill mechanism. The float drops down when the tank gets low on water. This closes the valve at the bottom of the tank, which turns on the water. When it’s done filling, the refill valve lifts up and shuts off, then opens again when the tank starts to fill with more water.
Faulty flapper chain
Your toilet’s flapper chain is the likely culprit if your toilet is randomly running for a few seconds. It can be too long or too short or simply stuck which influences the flushing of the toilet.
A flapper chain is what connects the handle to the flapper ball in your toilet’s tank, drawing up water with each flush. If it’s hanging too low or rubbing against the side of the tank every time you push down on the handle, it will catch on its surroundings and tug at its connection point (the flapper), which will cause water to refill your tank.
If this continues over time, it can use up quite a bit of additional water between fillings. The flapper chain should have a slack of ½ an inch in the middle.
Faulty fill valve
The fill valve of your toilet controls the amount of water that fills up the tank. A leak from this valve would consist of water constantly flowing into your toilet tank without being able to fill it up. The leaking water will then flow into the toilet bowl as a partial or full flush.
Faulty flush valve assembly
It may be that the flapper is not seating well or even leaks after being closed. In these cases, your toilet will continue to flush on its own until fixed. Your flush-valve assembly may just need some adjustment so that everything works properly again or a replacement is required.
Faulty flush-control mechanism
You could be having a faulty flush control mechanism somewhere in your toilet. For example, it could be stuck or not properly working which makes your toilet continuously run until you fix it. Faulty components like this may need replacement.
Faulty toilet handle
A faulty toilet handle can cause a toilet to run continuously. This means that the toilet handle is not coming back up after you pull it down, causing the flapper to stay open. The toilet handle may just be stuck or broken and this will determine the fix.
Sensor malfunction
Some advanced toilets might also have an automatic sensor installed inside of them for various purposes including triggering the flushing function. If that sensor malfunctions then your toilet will not stop running occasionally until you get someone to fix it or replace it altogether.
Wrong water level
The wrong water level in the toilet tank can cause the fill valve to activate for a couple of seconds which can cause it to run constantly. This wastes water. The water level in the toilet tank should be 1 to 2 inches (2.5 – 5 cm) below the fill valve. The refill tube should be at least 1 inch higher than the overflow tube.
Leaky seals
The seals and gaskets can also cause water to leak, which may cause the flapper or ballcock assembly to drain too quickly. Leaking seals can be due to deterioration or damage.
If your toilet toilet runs every few seconds and it’s not the flapper (after replacing flapper), it’s the other causes on this list causing the problem.
How do you fix a toilet that runs randomly?
For a toilet that runs periodically, the fixes are as follows:
Clean the toilet flapper
If the toilet flapper is dirty, it can cause water to run randomly. Clean the flapper by removing the chain connecting it to the handle or lift arm. Cleaning it with freshwater should be fine although you can use vinegar as well. However, if you are using a chemical cleaner make sure to rinse off any excess.
In this step, you can simply clean the whole toilet tank for any debris or dirt that may cause issues on the other part of the toilet tank.
Adjust the water level in the toilet tank
Loosen or tighten the screw on a float arm to lower the water in a toilet. For ball floats, simply bend the lever downwards to lower the water level in the tank. Adjust the length of chain so that it’s just long enough to stop the ball or float from touching the flush valve.
The chain may simply need to be untangled to work as required. Ensure you get the at least ½ inch of slack in the chain. Adjust the water level until the toilet stops running.
Replace cracked gaskets
Remove an old gasket from the float arm using pliers. Press in a new rubber gasket on top of the screw where you removed the old one, then re-tighten screw into place. After this, your tank will be able to adjust automatically with any changes in pressure or temperature without faulting again.
Replace a leaking flapper valve
Replace the toilet flapper as follows:
- Disconnect the water supply to toilet by turning off valves located below the tank behind toilet.
- Flush the tank and let all water drain out of the bowl and the tank completely.
- Remove the old flapper valve from the tank by unhooking the chain on the overflow tube in the back of toilet.
- Install the new one by lining up the holes for the tube and screws with the overflow tube. Adjust the chain so it hangs about an inch above the screw opening on top of flapper when valve is shut, then tighten it securely into place.
- Replace all the parts removed in reverse order, carefully securing each part in place before continuing with the next step.
- Test the toilet for leaks by pouring a bucket of water into the bowl to test flush mechanism and refill tank if necessary.
- Adjust the float level again if needed after this step.
The whole process takes less than 10 minutes.
The Korky 100BP Ultra High Performance Flapper is one of the best thanks to its universal fit. This means that it’ll fit on most toilets without problems.
Fix or replace a faulty toilet handle
The first step is to determine if the toilet handle needs to be replaced or repaired. Open the toilet tank then check the position of the toilet handle or button. If it’s stuck in one position, try releasing it. If it’s not possible or the handle/button is broken, you need to replace it.
Note down the model and type of toilet then head over to the store to buy a new handle. Most come with easy-to-follow instructions. In any case, if you can’t fix the handle yourself, find a handyman to do so.
Replace the float ball
Replace the float ball if it is damaged by turning it counterclockwise with your hand until it releases from the threaded rod. Then, tighten the new ball firmly onto the rod. If the ball appears to be intact yet loose, simply remove and fasten it again.
Replace the fill valve
A faulty fill valve needs to be replaced. A new fill valve can be purchased at a local hardware store. Replace the old fill valve according to the instructions on the packaging and test out your toilet. This will stop your toilet from running on and off by itself.
Recalibrate or replace the toilet sensor
If the flush sensor of your toilet makes the toilet flush intermittently, simply recalibrate it so that it only flushes when the toilet needs to be flushed. If it can’t be recalibrated, replace it with a new one.
These fixes should restore the normal functioning of your toilet and save you money in the process. If you can’t perform any of these tasks, call for a plumber who will charge you anything from $50 to $200. If you notice any air bubbles in the toilet, it could be a clog in the toilet instead.