A water heater that starts making unusual sounds, popping, rumbling, banging, or hissing, is telling you something. These sounds aren’t normal operating sounds. They’re symptoms of specific conditions inside the tank that, if left unaddressed, can shorten the life of the unit significantly or lead to more serious problems.
At Penguin Air, Plumbing & Electrical, our licensed plumbers service water heaters throughout the Phoenix area. Here’s what different water heater noises indicate and what to do about each.
Popping or Rumbling: Sediment Buildup
Popping or rumbling noises are the most common water heater complaint, and in Phoenix they’re almost always caused by sediment accumulation at the bottom of the tank. Phoenix’s water supply is high in calcium and magnesium, minerals that precipitate out of the water and settle as a layer of scale on the bottom of the tank.
When the water heater’s burner fires or the heating element activates, water trapped below the sediment layer is superheated and forces its way up through the sediment, creating the popping and rumbling sounds you hear. This process:
- Reduces the water heater’s efficiency (the sediment acts as an insulating layer between the burner and the water)
- Causes “hot spots” on the tank bottom that accelerate corrosion
- Stresses the tank walls through repeated pressure fluctuations
- Significantly shortens the service life of the unit
The fix is a water heater flush, draining the tank to remove accumulated sediment. For heavily scaled tanks, multiple flushes or professional descaling may be needed. Annual flushing prevents significant buildup from accumulating in the first place.
Hissing or Sizzling: Small Leak or Condensation
A hissing or sizzling sound, especially on a gas water heater, can indicate a small water leak dripping onto the burner or hot surfaces. Even a minor drip creates a distinctive sizzling when it contacts the heat source. Inspect the T&P valve discharge pipe, the cold water inlet/hot water outlet connections at the top of the tank, and the area around the burner compartment for signs of moisture.
On electric water heaters, a hissing sound can sometimes come from the heating elements as sediment is disturbed during heating. On a new water heater, brief hissing during the first few heating cycles is sometimes normal condensation on the tank exterior burning off.
Banging or Knocking: Water Hammer
A banging sound that occurs when you turn a faucet or appliance on or off isn’t actually coming from the water heater, it’s water hammer. The sudden stop of fast-moving water in the supply pipes creates a pressure shockwave that produces a bang or thud. Water hammer is hard on pipe joints and valves and should be addressed.
The fix for water hammer is typically installing water hammer arrestors on the supply lines near the affected fixtures, or ensuring the water supply pressure is within normal range (under 65 psi). A plumber can assess the cause and recommend the right solution.
Ticking or Tapping: Normal Expansion Sounds
Soft ticking or tapping sounds as the water heater heats and cools are usually just thermal expansion in the pipes, normal sounds from metal expanding and contracting. If the ticking is loud, persistent, or accompanied by other symptoms, it’s worth having a plumber inspect the unit, but mild thermal ticking is generally harmless.
Screeching or Whining: Valve Issues
A high-pitched screeching or whining sound, particularly when hot water is running, often indicates a valve that’s not fully open. Check the shut-off valve on the cold water inlet at the top of the water heater and confirm it’s fully open. Partially closed inlet valves can create a high-pressure whistle as water is forced through the restriction.
How to Prevent Water Heater Noise in Phoenix
Annual water heater maintenance is the most effective prevention. Our water heater service includes flushing the tank to remove sediment, inspecting and replacing the anode rod as needed, testing the T&P valve, and checking all connections. Installing a water softener dramatically reduces the rate of mineral scale accumulation in Phoenix’s hard water environment.
If your water heater is making unusual sounds, call Penguin Air, Plumbing & Electrical at (480) 525-5400. Our licensed plumbers serve Phoenix, Scottsdale, Mesa, Chandler, Gilbert, Tempe, and the surrounding Phoenix Valley.
Frequently Asked Questions
Is it normal for a water heater to make noise in Phoenix?
Mild thermal ticking and expansion sounds are normal. Popping, rumbling, banging, or hissing sounds are not, they indicate sediment buildup, leaks, water hammer, or valve issues that should be addressed. In Phoenix’s hard water environment, sediment buildup begins faster than in most US cities, so annual flushing is particularly important.
Will flushing my water heater stop the popping noise?
In most cases, yes. If the popping is caused by sediment (the most common cause in Phoenix), flushing the tank removes the accumulated scale and eliminates the condition that creates the noise. For tanks with heavy, hardened scale, professional descaling may be needed, scale that has calcified into rock-like deposits may not flush out with water alone.
How often should I flush my water heater in Phoenix?
Once per year is the standard recommendation. In Phoenix, where water hardness is significantly above the national average, some homeowners benefit from flushing twice per year. If you install a water softener, the reduced mineral content in the water will dramatically decrease sediment accumulation.
My water heater is making noise and it’s 12 years old, should I repair or replace it?
At 12 years, a Phoenix water heater is approaching the end of its typical service life (10-15 years). If the noise is caused by heavy sediment buildup, a flush may provide a few more years of service, but the tank may already have corrosion damage from years of scale buildup. A plumber can inspect the anode rod and tank condition to help you decide whether repair or replacement is the wiser investment.
About Penguin Air, Plumbing & Electrical
Penguin Air, Plumbing & Electrical has been serving Greater Phoenix homeowners with trusted HVAC, plumbing, and electrical services since 2011. Founded by Wade Rusk and William Hallett, Penguin is locally owned and operated, available 24 hours a day, seven days a week. Our licensed, background-checked technicians serve Phoenix, Mesa, Scottsdale, Chandler, Gilbert, Tempe, Glendale, and communities throughout the Phoenix Valley.
Call Penguin Air at (480) 525-5400 to schedule service today.