Q: When we run the water in our house, particularly when it is cold, the pipes make a harmonic noise for a while after the water is shut down. Curiously, when we sit on the upstairs toilet the pipes make a harmonic noise without the water running. The house is about 40 years old and this just started last winter and now is starting up again. Any ideas of what causes this, and is there a solution?

A: Harmonious water lines, huh? Do they play any particular tune? We hope your pipes aren’t subjecting you to heavy metal.

Kidding aside, we believe you are describing a form of what is known as a “water hammer,” a colorful euphemism for noise in water supply lines.

Water hammers come in many different versions – from a severe “bang” to an imitation of a machine gun to a wheeze or even, as in your case, harmonic noise. Water hammer is caused by a sudden change of pressure inside the pipes, often when a faucet or valve closes quickly or a valve is faulty.

The cause is best explained by a quick physics lesson. When the tap is turned on, the pressure built up in the water line is released. At that point water is moving through the pipe. When the tap is shut off, water movement stops. Because water does not easily compress, this sudden stop creates a shock wave that travels back through the pipe until it hits a point of impact at a bend in the line (a tee or elbow). The impact causes the pipe to vibrate, as if you hit the pipe with a real hammer.

Severe water hammers may damage pipes at the joints. With a water hammer that is consistent and loud, a licensed plumber should be contacted to determine if the line should be fitted with an air chamber or a surge arrester.

As for your harmonious water lines, the good news is we don’t believe you have a severe problem. To silence the singing, the first step is to isolate the source. Start with your faucets, including sinks, bathtubs and showers. Turn on one faucet at a time and note if the pipes sing.

Since your home is 40 years old, our bet is that some do and some don’t. For the ones that do, we suspect faulty washers. The solution, replace the washers. Part of a good home maintenance schedule is to change the washers in faucets on a regular basis. Every five years or so will do, depending on usage.

But based on your question, we think the source of your siren song is somewhere else – in your commode. Since your problem seems to be linked with your upstairs toilet, we think the prime suspect is a faulty fill valve in the toilet tank.

Ever notice that after you flush a toilet the tank fills moderately at first and then slows to a trickle at the end. This design feature is to prevent a sudden change in water pressure that could destroy the valve. After years of wear and tear, gaskets and other parts can wear out, stopping the fill valve from working properly.

When the valve is on its last legs, parts do not seat properly, vibrations are created and, voila, you have singing pipes.

Most likely, the fill valve is being jostled ever so slightly and releasing water into the toilet tank.

Again, the solution is simple. Replace the fill valve. Go to the local home center or plumbing supply house and buy and install a replacement fill valve. This is something you can tackle yourself. We recommend that you remove the old valve, take it with you to the store and try to get a replacement that matches.

A word of caution here, be gentle in removing the old valve. Toilet tanks are porcelain and can be broken easily. If the connection on the fill valve is metal, some WD-40 on threads to lubricate them prior to removal is a good idea.

Also we recommend that you replace the flapper at the same time.

As for this occurring more in the winter months, it’s likely that the cold weather is affecting the expansion and contraction of your plumbing system, helping to cause your singing pipes.


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