A water heater is a metal drum with a burner under it, sitting in a basement, quietly doing its job for a decade. When it starts making noise, it is usually telling you something specific. Here is how to read it.
Popping and rumbling
This is the common one, and it is sediment.
Springfield is on hard water. Every gallon that goes through your heater leaves a little calcium and magnesium behind, and it settles on the bottom of the tank where the burner is. Over years it builds into a crust an inch or more thick.
What you are hearing is water trapped underneath that crust. It gets superheated, turns to steam, and forces its way up through the sediment layer. That is the pop. A deep rumble is the same thing at a larger scale, or the sediment bed itself shifting.
It is not dangerous today. What it is doing is insulating the burner from the water, so the burner runs longer for the same result, which shows up on your gas bill and cooks the bottom of the tank from below. A tank that pops for years fails earlier than one that does not.
The fix is flushing it, which is straightforward and worth doing annually in water like ours. If it has never been flushed and the tank is eight or more years old, be aware that flushing a heavily crusted tank sometimes reveals a leak the sediment was plugging. That is not the flush causing damage, it is the flush finding damage.
Ticking or light tapping
Usually harmless. This is normally the heat traps, the little valves in the supply lines at the top of the tank, or it is thermal expansion in the pipes themselves as hot water moves in and metal grows against a strap or a joist.
If the ticking follows the heating cycle and stops when the burner stops, it is expansion. You can sometimes stop it by loosening whatever strap the pipe is fighting.
Screeching or a high whine
This is water forced through a restriction. Most often a partly closed valve somewhere on the inlet or outlet, or a failing temperature and pressure relief valve.
Check the obvious thing first: is a shutoff valve only partway open? Somebody working on something may have left it that way.
If the valves are all fully open and it still whines, the T&P valve is the suspect and that is worth a call, because that valve is the safety device.
Banging when a tap shuts off
That is not the heater. That is water hammer, the shock of moving water stopping suddenly, and it travels through the whole system. Common after a washing machine or dishwasher solenoid closes.
It is fixable with arrestors, and worth fixing, because that shock loosens joints over time.
Boiling, gurgling, or the sound of a kettle
Shut it off.
A tank that genuinely sounds like it is boiling may be overheating, which means the thermostat or the T&P valve is not doing its job. A water heater that cannot relieve pressure is the one failure mode on this list that is actually dangerous.
Turn the gas control to off, or kill the breaker on an electric unit, shut the cold supply valve at the top of the tank, and call. Do not open the T&P valve to test it in this situation.
This is rare. But it is the one to know.
How old is it?
Most tanks in this area go ten to twelve years. If yours is past that and it has started talking to you, the calculation changes. Money spent on a fifteen-year-old tank is often money spent twice.
The date is usually encoded in the serial number on the label, often the first four digits as month and year. If you cannot read it, we can.
What actually extends the life
Flush it annually. Check the anode rod every few years, that is a sacrificial metal rod that corrodes so the tank does not, and replacing a twenty dollar rod at year five is the single highest-return thing you can do for a water heater. Keep the thermostat at 120 degrees, which is hot enough for the house and easier on the tank than 140.
Most people do none of these and get ten years. People who do them get closer to twenty.
If yours is making a noise you cannot place, call and describe it. Half the time we can tell you over the phone whether it can wait.
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