Why is my water heater making noise?

Popping or rumbling from a water heater is usually sediment buildup on the bottom of the tank — minerals harden, water trapped underneath boils, and the tank rumbles. It shortens the heater's life and raises energy bills. Flushing the tank often quiets it; a heater over 10 years old that rumbles is usually telling you replacement is near.

Likely causes

• Sediment buildup — Popping/rumbling. Most common in hard-water areas and tanks never flushed.
• Water hammer — Banging in the pipes (not the tank) when valves close fast — a pressure/plumbing issue, not the heater itself.
• Loose heating element — Humming or vibrating on electric models.
• Pressure buildup — Hissing or whistling can signal a faulty temperature-and-pressure relief valve — treat this one seriously.

What you can check yourself

• Identify the sound: popping/rumbling = sediment; hissing/whistling = stop and read the next line.
• If it's sediment and the heater is under ~8 years old, a tank flush may fix it.
• Check around the base for leaks or rust — either changes the answer to 'replace'.

Typical cost

A professional flush in Denver, CO typically runs $150–$300. Replacement water heaters run $1,400–$2,800 installed for a standard tank.

When to call a pro

Hissing, whistling, any leak, or rust-colored water — shut the unit off and call. The relief valve is a safety device; don't troubleshoot pressure symptoms yourself.

Plumber pros in Denver, CO

• 1
  A -1 Plumbing Co. ★ Recommended

  Denver, CO · 13036290722
• 2
  A&H Plumbing

  Denver, CO · 7209988222

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Data by Servik — verified local pros from official license records and public sources. Cost figures are typical ranges, not quotes; a pro's written estimate is the real number.