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Why Does My Toilet Whistle When I Flush It?


Everyone wants a toilet that's clean as a whistle. But one that whistles at you when you flush it? Let's face it, most people don't want to hear that, even if it is on key! Some toilets have a whistle that's nice and soft; others sound closer to a screech. Whatever tune your toilet is whistling, it's telling you there's a problem that needs to be fixed.

Why Does My Toilet Whistle?

In most cases, the metal ballcock valve is vibrating as the toilet tank refills after flushing. The vibration is usually caused by:

  • A damaged fill valve gasket; or
  • Simple wear and tear that have worn down the valve itself.

A simple adjustment can sometimes eliminate whistling, but once it reaches screech level, it's only a matter of time before the fill valve fails completely. If you want to try and fix the problem yourself, it helps to have some basic plumbing knowledge.

Check the Water Supply Valve

The knob is located behind the toilet, next to the wall. To make sure it's completely open, turn it counterclockwise as far as it'll go. If you still hear a whistle, remove the toilet tank cover for the next step.

Inspect the Fill Valve

For older whistling toilets that use metal ballcock valves, this is usually your culprit. The valve is generally located in the left rear corner. Flush the toilet and listen for where the whistle is coming from. If it sounds like it's coming from the fill valve, check for any buildup of mineral deposits that might be restricting the water flow. Wipe off any deposits with a damp rag. Flush the toilet again. Still hear a whistle? Try the next step.

Replace the Fill Valve

To stop the whistling, you can replace the gasket in a metal ballcock valve. Newer, plastic valves are also available and are less likely to whistle when they vibrate. They're also more efficient than older versions and help conserve water, saving you money on your water bill.

There are quite a few steps to replacing a toilet fill valve, but it's a fairly simple DIY task that only calls for a few tools.

  1. Turn off the water supply valve and then flush the toilet.
  2. Use an old towel or sponge to remove any remaining water in the tank.
  3. Disconnect both the old supply line from the toilet tank and the fill tube connected to the overflow pipe.
  4. Remove the fill valve by unscrewing the valve nut.
  5. Place the new valve in the tank and make sure the washers are correctly placed.
  6. Hand-tighten the lock nut on the threaded part of the fill valve underneath the tank.
  7. Use a wrench to reattach the water supply line to the bottom of the fill valve.
  8. Turn the water back on and check for leaks.
  9. Adjust the float so it sits about 1" below the overflow pipe.

Finally, once the tank refills and the water stops running, flush the toilet to ensure there are no leaks-and no whistling!

Call Your Plumber 

If your toilet is still whistling, or if you'd like help installing a new fill valve, call David Gray Plumbing today at (904) 605-8190. You can also contact us online.