Water heaters make some sounds during normal operation. A new or much louder sound is worth noticing, particularly if it comes with leaking, poor hot-water performance or a displayed fault.
Describe what changed
Is it a click when the burner starts, a rumble while the unit heats, or a knock when a tap closes? A knock can sometimes come from piping rather than the heater itself. Record where you hear it, when it happens and whether the water temperature has changed.
Do not diagnose a heater by sound alone. Different faults can sound similar, and opening a gas or electrical appliance can create risk.
Know when to call
If you see water around the tank, hear an unusual continuous hiss, smell gas, or see an error code, stop using the appliance as appropriate and seek qualified help. For gas odour, go outside and follow FortisBC’s emergency guidance. For other changes, contact our water-heater team with a short description or recording.
Make the service call more useful
Say whether the unit is a storage tank or tankless, and whether the sound comes from the heater, a nearby pipe or a fixture. Note whether it starts when a tap opens, during heating, or after a tap closes. A short recording and a photo of the rating label can help when the sound is intermittent.
Rumbling in a storage tank can be one reason to review sediment maintenance, but it is not a diagnosis. Banging when a tap shuts may be a piping issue. The technician needs to check the actual system before recommending a flush or repair. Our tank maintenance guide explains why service instructions vary by model.