Why Is My Water Heater Making Rumbling or Popping Noises?

If you’ve noticed strange rumbling, banging, or popping sounds coming from your water heater, you’re not alone. Many homeowners in Phoenix experience this issue, especially in areas with hard water. While it might seem minor at first, these noises are a warning sign that your system may be struggling and could lead to costly repairs or even a full replacement if ignored.

What causes rumbling or popping noises in a water heater?

1. Sediment buildup at the bottom of the tank

The most common cause is sediment accumulation. Minerals like calcium and magnesium settle at the bottom of the tank over time. When the burner heats the water, steam bubbles get trapped under this sediment layer, creating popping or rumbling sounds as they try to escape.

This is especially common in Phoenix due to hard water.

2. Overheating water

If your thermostat is set too high, the water may boil slightly at the bottom of the tank, creating loud popping or knocking sounds.

3. Scale buildup on heating elements (tankless or electric units)

In electric or tankless systems, minerals can coat the heating elements, causing uneven heating and noise during operation.

4. Aging water heater

Older systems accumulate more debris and lose efficiency, increasing the chances of strange noises.

Is a noisy water heater dangerous?

Not immediately, but it’s a sign that something isn’t working efficiently. Ignoring it can lead to:

• Reduced hot water supply

• Higher energy bills

• Cracked tank lining

• Premature system failure

• Water leaks

Addressing the problem early can save you thousands in repairs or replacements.

How to fix a rumbling or popping water heater

Step 1: Flush the tank

Draining and flushing the tank removes sediment buildup. This should be done at least once a year, especially in hard water regions like Phoenix.

Step 2: Lower the temperature

Set your thermostat to around 120°F to reduce overheating and pressure stress.

Step 3: Install a water softener

A softener reduces mineral accumulation and extends the life of your water heater.

Step 4: Schedule professional maintenance

A licensed plumber can safely remove stubborn sediment and inspect internal damage.

When should you call a plumber?

You should contact a professional if:

• The noise is getting louder

• You hear banging instead of soft popping

• Your water smells metallic or looks rusty

• Hot water runs out quickly

• You notice leaks near the unit

A plumber can assess whether repair or replacement is the best option.

How to prevent future water heater noises

• Flush the tank annually

• Maintain proper temperature settings

• Schedule yearly inspections

• Use water treatment solutions for hard water

• Replace the anode rod when needed

Preventative care keeps your system efficient and quiet for years.

Need expert water heater service in Phoenix?

Call Vertical Plumbing at (480) 577-8720