Hisses, squeals, thumps, and honks are sounds more commonly found around a freeway or industrial area rather than in your own bathroom. But when your toilet makes noises after flushing, you just might hear an unexpected hammer or hiss.
The good news is that when your toilet makes noises after flushing, the cause is usually easy to diagnose. Toilets are simple devices with very few parts, so most homeowners can fix their own toilets and stop those noises for good.
Toilet Hisses for a Long Time After Flushing
After you push the toilet lever, you may hear a hissing sound, like water running. While this is the normal sound of the toilet refilling its tank, the sound continues for longer than the expected one to three minutes. The seal in the toilet fill valve might be corroded or deteriorated. The seal can be cleaned or replaced. If this does not fix it, replace the entire toilet fill valve.
How to Fix It
- Turn off the water to the toilet. Flush the water to drain the tank.
- Unclip the narrow rod (called a tank water level adjustment screw) from the side of the toilet fill valve.
- Push down on the cap of the toilet fill valve and turn it counter-clockwise until it releases from the toilet fill valve. Hold the fill valve in place with your other hand as you turn.
- Remove the cap.
- Remove the seal from the cap. If the seal is cracked or deteriorated, replace it. Clean the seal if it is in good condition.
- If the top of the toilet fill valve has mineral deposits, slowly turn on the water supply to cause water to burble from the screen. Make sure that the water flow removes the deposits. Turn the water off again.
- Replace the cap of the toilet fill valve. Turn the water back on.
Toilet Squeals or Whistles After Flushing
After you flush the toilet, the toilet makes a high-pitched whistling or squealing sound. The sound is brief and it ends when the water is finished filling the tank. In most cases, a dirty or bad toilet fill valve seal is the cause of a squealing or whistling toilet. Cleaning the valve seal or replacing it entirely usually will cure the whistling sound.
How to Fix It
- Shut off the water supply and flush the toilet.
- Note and remember the position of the valve arm.
- Lift the arm of the float. With one hand, hold the fill valve stem.
- With your other hand, twist the valve cap a quarter turn counterclockwise.
- Lift the valve cap and unhook it.
- Inspect the valve area for debris. If there is debris, open the water supply valve just a little to permit water to flow through and clear the debris.
- Remove the toilet fill valve seal. In most cases, it's easier and more effective to replace the valve seal rather than clean it.
- Press the new toilet fill valve seal in place.
- Replace the valve cap, lock it into place, and turn on the water.
Toilet Makes a Flushing Sound on Its Own (Ghost Flush)
Long after you flush the toilet, the toilet makes a flushing sound all on its own. Your toilet is either partially or completely flushing on its own, independent of you pressing the lever.
This toilet sound is often called a ghost flush or phantom flush because it sounds eerily like someone flushing the toilet, even though no one is in the room. You may need to adjust the refill tube that attaches to the overflow pipe or you may need to replace the toilet flapper.
How to Fix It
- Do not empty the tank or flush the toilet.
- Remove the refill tube from the overflow pipe. The end of the refill tube should not be below the water line.
- If the tube does extend below the water line, insert it into the overflow tube but not as far as before.
- If the refill tube is too long, snip a bit of the end with scissors and insert the tube back into the overflow pipe.
- Turn off the water supply to the toilet and flush the toilet.
- Soak up water at the bottom of the tank with a towel.
- Remove the toilet flapper by unclipping the chain that goes to the toilet handle arm.
- Remove the flapper ears from the pegs.
- Remove the flapper.
- Fit the ears of the replacement flapper over the pegs on the flush valve tube.
- Attach the chain.
- Turn on the water supply, let the tank fill up, and test-flush the toilet.
Toilet Bangs or Hammers After Flushing
After you flush the toilet, the toilet makes a loud bang, thump, or hammer sound. The sound occurs after the toilet tank has finished filling up.
This toilet hammering sound is sometimes heard in other fixtures and appliances, especially washers. Quickly cutting off the flow of water causes water supply pipes to bang within the house—against studs, joists, and beams. Water hammer can be easily fixed by installing a mini in-line single fixture water hammer arrester.
How to Fix It
- Turn off the toilet's water supply and flush the toilet. Soak up water in the tank with a towel.
- On the outside of the toilet tank, remove the water supply hose from the bottom of the toilet by turning it by hand counter-clockwise. Let the water drain into a container.
- Screw the mini-arrester onto the bottom of the toilet.
- Screw the water supply into the bottom of the water arrester.
- Turn the water supply on again, let the tank fill up, and test-flush the toilet.
Toilet Moans or Makes Horn Noise After Flushing
After you flush the toilet, the toilet makes a loud horn-like, moaning, or foghorn sound. The toilet may also sound like it is humming or vibrating. The sound is brief, but it happens nearly every time you flush the toilet.
When the water supply valve to the toilet is partially closed, this can create a vibration that results in a horn-like or moaning sound.
How to Fix It
- Turn the water supply valve to the toilet off.
- Turn the water supply valve back on, making sure that it is fully open.
- Flush the toilet to test it.
If that fix does not stop the toilet from moaning, replace the toilet's water supply valve.
- Turn off the home's main water supply.
- Grasp the pipe extending from the wall with channel-lock-type pliers. Wrap the pipe with a cloth to protect the surface of the pipe.
- With a second set of pliers, turn water supply valve off of the pipe.
- Clean the threads of the pipe.
- Wrap the pipe's threads two or three times clockwise with plumber's tape.
- By hand, turn the water supply valve onto the pipe. Finish by tightening with pliers.
- Turn on the main water supply and then turn on the supply to the toilet.
Toilet Makes a Bubbling or Gurgling Sound After Flushing
After you flush the toilet, the toilet makes a deep gurgling or bubbling sound. The sound appears to be coming from the toilet base or bowl. The toilet might be partially blocked, the refill tube may have come loose, or a vent stack might be blocked.
How to Fix It
- Plunge or auger the toilet. Even if the toilet does flush, it might be partially blocked.
- If that does not help, open up the toilet tank. Locate the refill tube, a thin tube leading from the toilet fill valve to the overflow pipe.
- Make sure that the refill tube is attached to the overflow tube, as it may have detached.
- Check the vent stack on the roof. While not common, it might be blocked by a bird's nest or other debris.
- If those fixes do not work, contact a plumber to clear out the sewer main.