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What Makes Water Pipes Whistle?

residential plumbingThe whistling sound coming from water pipes can tread the line between soothing and alarming. This sound is due to high water pressure, and is a sign that something bad is about to happen to the plumbing system of your property.


When whistling can be heard from a toilet fill valve, tap, or somewhere within the wall, take it as a sign of water flowing. When the sounds are coming from a valve or tap, it is a sign that the washer or gasket has worn out, and the sound produced is what happens when water passes that part. If the sound is coming from the pipes, it is due to high water turbulence, and reasons for this are:

  • High water pressure
  • Mineral build-up in the pipe
  • Water is erratically flowing through a badly installed fitting, like a tee or elbow.
  • Air has entered the pipes, causing the formation of a bubble that keeps water from flowing.
  • There is a partly open inline valve. Inline valves must be completely open.

The Pressure is On

The problems mentioned above have grave consequences. For instance, mineral build-up can loosen and block the pipe, air bubbles can prevent the flow of water, and improperly installed fittings causes whistling and vibrations, which weaken joints and cause leaks. High pressure is the worst of these problems, though, since it causes joint failure and leaks in several areas. If the leak is behind walls, it cannot be found until the walls are severely damaged.

  • Assessing Water Pressure

To find out if water pressure is high, you can do a simple test. This test will involve a pressure gauge, which you should screw on a threaded tap (preferably one located outdoors or the laundry area). Once you have done so, turn the tap on and take a look at the needle. The water pressure must not exceed 60 PSI. If you own a well, the gauge must stay connected until the pump will cycle on and finishes pressurising the system.

  • Pressure Reduction

There are two ways to reduce pressure:

  • Pressure regulator adjustments. If the house is connected with the municipal water supply, a pressure regulator needs to be set up near the meter. With a wrench, turn the nut at the top part of the pressure regulator clockwise to reduce pressure.
  • Adjusting the cut-off pressure of the pump. If the well is your source of water, you can set the cut-off pressure of the pump lower to adjust pressure. This adjustment, which should only be done by plumbing professionals as it involves exposing electrical terminals, is for the pressure switch.

Purging the Air

When air enters the water pipes, it goes up the highest point (at upstairs bathrooms or walls by those bathrooms) and will stay there to create a bubble. To purge air, you should first switch on each tap in the bathroom while flushing the toilet to increase water flow. This increase in water flow should push all air out through one of the taps.

Pipe Replacement

Call a plumber if the whistling is from old steel pipes or if the whistling sound is from a specific fitting. The former is because of corrosion within the pipes and it cannot be fixed any other way. As for the latter, rerouting the pipes is the only way it can be sorted out.