Why does my water heater make noise?

Popping, rumbling, or crackling noises from a water heater are caused by sediment buildup at the bottom of the tank. As the burner heats the water, trapped sediment creates steam bubbles that make popping sounds. Flushing the water heater annually removes sediment and reduces noise. Sizzling sounds may indicate a leak onto the burner. If noises persist after flushing, the tank may be deteriorating and replacement may be needed.