Fixing A Toilet That Makes Noises After Flushing

We all expect a certain amount of noise to come from the toilet when we flush it. After all, that’s a lot of fast-moving water making its way down the drain. Once the flushing process is complete, however, a toilet should be seen and not heard until the next time it is flushed. 

When a toilet continues to make noises after flushing, though, it can be annoying, to say the least. While some noises are harmless, others may indicate a problem that needs immediate attention. It can be a challenge trying to figure out which noises are nothing and which ones need repair, so continue reading as I cover several noises a toilet can make and how to fix each one. 

6 Toilet Noises and How to Fix Them

In this section, I will discuss specific noises a toilet makes and what you can do to remedy the situation. The good news is that as toilets go, there are few moving parts, and most things can be fixed easily by most do-it-yourselfers. If, however, you are uncomfortable making these repairs, or have no idea what is causing the noises you hear, don’t hesitate to call in a licensed plumber. 

1. Hammering or Banging Noise

A hammering or banging noise heard after flushing is usually nothing to be concerned about. This noise is caused by the sudden stop of water flowing through your home’s pipes. The noise is actually the water sloshing around in the pipes because it was stopped in its tracks suddenly when the water supply shut off. You may hear this hammering or banging noise in other parts of your home, too. It is especially common with washing machines as water goes on and off several times during each washing cycle. 

If you hear this banging sound after your toilet completes its flushing cycle, you can try lessening the water pressure coming into the tank by adjusting the water inlet valve. If this doesn’t work to stop the noise, your next option is to install a water hammer arrestor where the water supply connects to the bottom of the toilet tank. Here’s how. 

  1. Turn the water supply off by turning the water inlet valve all the way clockwise. Flush the toilet to drain the water from the tank. If any water remains in the tank, use a towel or sponge to sop it up. 
  2. Disconnect the water supply hose from the bottom of the toilet tank by turning it counterclockwise. There may be water inside the hose, so have a bucket handy to drain the water into. 
  3. Install the water hammer arrester by screwing it into the fill valve at the bottom of the toilet tank. 
  4. Reattach the water supply hose by screwing it by hand into the arrester. 
  5. Turn the water back on and allow the tank to fill. Once the water shuts off, give your toilet a test flush to ensure the hammering noise is gone. 

2. A Foghorn Noise

If your toilet makes a loud horn-like sound every time you flush it – almost like it is guiding ships into the harbor – you may have a water supply issue on your hands. While the sound is brief, it happens every time you flush, which can be extremely annoying. Luckily, this noise does not indicate a serious problem, but you should fix it so you can use the bathroom in peace. 

To fix a foghorn noise coming from your toilet, follow these steps. 

  1. It could be that the water supply valve isn’t open all the way. Try turning the valve clockwise as far as it will go to close it. 
  2. Turn the valve counterclockwise as far as it will go to open it. 
  3. Flush the toilet to see if the horn noise is gone. 

If this doesn’t fix the issue, try replacing the water supply valve.

  1. Turn the water off to the toilet.
  2. Turn your home’s main water supply off.
  3. Wrap a cloth around the water pipe coming from the wall behind the toilet and use a pair of pliers to turn the old water supply valve off. 
  4. Clean the threads and apply the plumber’s tape clockwise around them. 
  5. Turn the new water supply valve onto the pipe by hand and tighten it with a pair of pliers. 
  6. Turn the main water supply back on and check for leaks. If there are none, turn the water back on to the toilet. 
  7. Test flush. The foghorn noise should be gone. 

3. Persistent Hissing Sound

A hissing sound is normal when any toilet is flushed. The hissing is the sound of water rushing into the tank. If the hissing sound continues longer than it should, however, it might indicate an issue with the toilet’s fill valve. One of two things could be happening with a persistent hissing sound: the fill valve’s seal is worn or corroded, or the fill valve itself is bad. Here’s what you need to do. 

  1. Turn off the water supply to the toilet. Flush it to drain the water from the tank. 
  2. Locate the tank water level adjustment screw (it is a narrow rod attached to the side of the fill valve) and unclip it. 
  3. Push down on the cap on top of the fill valve. Turn it counterclockwise to remove it. Use your other hand to hold the fill valve in place as you turn the cap. 
  4. Remove the seal from the cap and inspect it for wear or damage. If you see any, replace the seal. If the seal looks to be in good shape, clean it off and return it to the cap. 
  5. Inspect the top of the fill valve to make sure it is clean. If mineral deposits have built up on it, turn the water supply on slightly to allow water to rinse the residue away. Turn the water back off. 
  6. Replace the cap on the fill valve and turn the water back on. 

If your toilet continues to hiss after checking the fill valve seal, the issue might be caused by a worn-out flapper. The flapper is that round rubber piece you see at the bottom of your toilet tank. Its job is to open and close to allow water to flow into the bowl. If this rubber seal is cracked or deteriorated, it cannot create a watertight seal and water will continue to run into the bowl creating a constant hissing sound. 

To replace the flapper: 

  1. Turn the water supply off and flush the toilet. Sop up any remaining water in the tank with a towel or sponge. 
  2. Unclip the old flapper from the chain. 
  3. Clean the bottom of the tank where the flapper rests to ensure a tight seal.
  4. Attach the new flapper to the chain. 
  5. Turn the water back on, let the tank fill completely, and give your toilet a test flush. 

Another cause of hissing noises after flushing is an incorrectly aligned float. The float (whether cup or ball) tells the toilet when to stop filling. If the float is set too high, water will continue to run into the tank and spill into the overflow tube. This creates a constant cycle of filling and draining that causes the hissing sound. 

To fix this issue, adjust the float by lowering it to just below the level of the overflow tube. 

4. Gurgling or Bubbling

A gurgling or bubbling noise coming from your toilet is probably the most difficult to diagnose. This issue is usually caused by a blockage somewhere. The blockage may be in the toilet itself, in the sewer vent on the roof, or in your home’s main sewer line. It may also be caused by a loose or detached refill tube inside the toilet tank. Start by eliminating the toilet as the problem first. 

  1. Use a flange plunger to attempt to break up the blockage. Even if your toilet flushes, it may still be partially blocked, thus the gurgling sound. You can also try using a toilet auger to dislodge the clog. 
  2. If the toilet isn’t clogged, remove the lid from the tank and check to see if the refill tube is securely connected to the fill valve and the overflow tube. 
  3. If the toilet isn’t clogged and the refill tube is securely in place, the next place to check is the sewer vent located on the roof of your home. It is rare, but sometimes this vent can become blocked by birds’ nests or the like, which can wreak havoc on your home’s sewer system. You may need to call in a plumber for this as removing a blockage in the vent pipe requires climbing on the roof and specialized equipment. 
  4. Lastly, if none of these fixes resolves your gurgling toilet issues, there is likely a blockage in your home’s main sewer drain, in which case, you need to call a plumber A.S.A.P. because it could cause serious damage if left unchecked. 

5. Ghost Flushing

Ghost flushing, sometimes called phantom flushing, is essentially a toilet that flushes itself intermittently. This occurs when the refill tube is not adjusted correctly or the flapper at the bottom of your toilet tank is bad. The flushing sound you hear is eerily similar to the sound the toilet makes when you push the handle, but it may or may not be a full flushing sound. 

The noise can be disconcerting, but all it really is is water slowly seeping into the bowl, and when the water level in the tank lowers to below the fill level, the water turns on to refill the tank. 

To fix this issue, try adjusting the refill tube first. 

  1. Remove the lid from the toilet tank. Locate the refill tube. 
  2. Remove the refill tube from the overflow tube. It should not be below the water line. 
  3. If the refill tube does extend below the water line, reinsert it into the overflow tube making sure not to insert it as far as before. 
  4. If the refill tube is too long, use a pair of scissors to snip off a little bit before reinserting it. 

If adjusting the refill tube doesn’t stop the ghost flushing, replace the flapper following the steps outlined above in the ‘toilet hissing’ section. 

6. Squealing or Whistling Sound

A toilet that squeals or whistles after flushing is likely a worn-out fill valve seal. The sound typically only lasts as long as it takes for the tank to refill. I covered the steps to clean and replace the fill valve seal in the ‘toilet hissing’ section above. In most instances of toilet squealing or whistling after flushing, it is recommended to simply replace the seal rather than attempt to clean it. 

Verdict: Fixing A Toilet That Makes Noises After Flushing

A toilet that makes noises after flushing can be perplexing, but in most cases, the fix is simple. In fact, most people can make the repairs themselves. From banging and hissing noises to squealing and gurgling sounds, toilets can make their presence known in some pretty weird ways. Luckily, by following the guidance above, you should be able to put a stop to the crazy noises coming from your toilet after you flush.

Plumber and HVAC Technician | Website | + posts

As a retired Master Plumber Jamie has over 30 years of hands-on experience, making his plumbing knowledge second to none. He has also worked on both residential and commercial HVAC installation and repair projects.