Popping or Rumbling: Sediment Buildup (Most Common)
The most common water heater noise in Sonoma County homes is a popping or rumbling sound. This is caused by sediment — mineral deposits from hard water — accumulating at the bottom of the tank. As the burner heats water beneath the sediment layer, water boiling through it creates the popping sound. It’s not dangerous, but it reduces efficiency and shortens tank life. Fix: annual flushing, or if severe, replacement.
High-Pitched Whining or Screeching: Water Pressure Issue
A high-pitched whine usually indicates water being forced through a partially closed valve — often the cold water inlet valve. Check that the inlet valve is fully open. If the noise persists, the valve may need replacement.
Ticking or Tapping: Expansion & Contraction
A regular ticking or tapping sound as the water heater heats up is usually normal — it’s the expansion and contraction of metal pipes. If it’s louder than it used to be or starts occurring randomly, have it checked.
Banging or Hammering: Water Hammer
A loud bang when the burner ignites or when water shuts off is called water hammer — pressure waves in the pipes. Water hammer arrestors (installed on supply lines) eliminate this. It can also indicate loose pipe straps.
Rumbling + Discolored Water: Time to Replace
If you have both noise and rusty or discolored water, your tank is likely corroding internally. This means replacement is needed soon — a corroding tank will eventually leak.
Related: Water Heater Repair & Replacement | Upgrade to Tankless