Why is my water heater making popping or rumbling noises?
Popping, crackling, or rumbling from a tank water heater is almost always mineral scale sitting on the bottom of the tank above the burner. Water trapped under the scale boils and pops as it escapes. It's a sign the tank needs flushing — and in Utah, it's a sign you should flush annually going forward.
Popping, crackling, or rumbling from a tank water heater is almost always mineral scale sitting on the bottom of the tank above the burner. Water trapped under the scale boils and pops as it escapes. It's a sign the tank needs flushing — and in Utah, it's a sign you should flush annually going forward.
Popping, crackling, or rumbling is almost always sediment — mineral scale that's fallen out of the water and sits on the bottom of the tank, directly above the gas burner on a gas unit. Water trapped underneath gets superheated, turns to steam, and pops out through the scale.
The burner also has to work harder to heat through the scale layer, so gas bills creep up at the same time. A full tank flush removes the sediment and quiets most units. If the popping returns within a month, the scale layer is thick enough that it's time to consider a new tank or a switch to tankless.
In Utah's hard water, flushing annually keeps this from becoming a recurring problem.
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Last reviewed April 1, 2026.