Why Is Your Water Heater Making Noise? Common Sounds and What They Mean
A quiet hum from your utility closet is one thing. But when your water heater is making noise like popping, banging, whistling, or even sounding like a jet engine, it's normal to wonder, "Why is my water heater making noise, and is it dangerous?"
The good news: most water heater noises are warning signs long before they're emergencies. They usually point to fixable issues, such as sediment buildup, high water pressure, or a loose part(s). A few sounds do require urgent attention, especially if you have a gas unit.
This guide breaks down the most common water heater sounds, what they mean, when you can try simple troubleshooting, and when it's time to call a pro for water heater repair and maintenance.
Do Water Heaters Make Noise Normally?
Yes, some noise is completely normal. A hot water heater making noise doesn't always mean something's wrong. You might hear:
- A low hum as the heating element or burner turns on
- Soft gurgling as water moves through the tank
- A gentle whoosh when the burner ignites on a gas water heater
- Light clicking when the thermostat cycles
These sounds are expected. The red flags are new, loud, or unusual noises, especially if your noisy water heater is also leaking, struggling to heat water, or is more than 10-12 years old.
If you're asking, "Is it normal for a water heater to make noise?" the short answer is: yes, some are. Violent banging, shrieking, or constant hissing? No.
The Most Common Water Heater Noises (and What They Mean)
1. Popping or Rumbling: Sediment Buildup
The most common complaint is a water heater making popping or rumbling noises, often after a shower or heavy hot water use. It can sound like a kettle boiling or gravel bouncing inside the tank.
What's happening: Over time, minerals in the water settle at the bottom of the tank. When the burner or heating element turns on, it has to heat through that sediment layer. Trapped water pockets superheat and burst through, causing the popping or rumbling sound.
Why it's a problem: Sediment acts like insulation. Your heater works harder, uses more energy, and parts wear out faster. A severe buildup can even cause your hot water tank to make a noise that sounds like a small explosion.
What to do: Most of the time, you can fix a water heater making a loud noise from sediment by flushing the tank. Many homeowners are comfortable performing a basic flush, but if you're not, scheduling professional water heater services is the safer and faster option.
2. Hissing or Sizzling: Possible Leaks or Gas Issues
A water heater making a hissing noise or sizzling sound is more serious, especially if you see moisture, drips, or steam.
Electric water heaters: Hissing can mean water is leaking onto the heating element. That's often due to a failing gasket, cracked element, or internal leak.
Gas water heaters: A hissing sound from a gas unit could be condensation hitting the hot burner or, in some cases, a potential gas issue.
Is it dangerous? It can be. Water near live electrical elements and gas leaks are not DIY problems.
What to do:
- Turn off the power to the electric heater at the breaker.
- Turn off the gas to the gas heater at the shutoff valve.
- Shut off the cold water supply if you see obvious leaks.
Then call a licensed plumber or water heater technician right away. This is not the time to experiment or ignore the noise.
3. Whistling or High-Pitched Screeching: Pressure or Valve Problems
If your water heater is making a high-pitched noise or whistling like a tea kettle, something is forcing water or steam through a small opening.
Common causes:
- Partially closed inlet or outlet valves
- A restricted or failing temperature and pressure (T&P) relief valve
- High water pressure in the home
Sometimes the fix is simple: a valve that isn't fully open. But whistling from the T&P valve can indicate dangerous pressure buildup inside the tank.
What to do: Make sure the main shutoff and water heater valves are fully open. If the whistling continues, or you're not sure which valve is which, have a plumber inspect it. Pressure issues are not something to gamble with.
4. Banging or Hammering: Water Hammer and Loose Pipes
A water heater making a banging noise or loud knocking when fixtures shut off is often caused by "water hammer." This happens when fast-moving water is forced to stop suddenly, sending a shockwave through the pipes.
What it sounds like: Loud thuds or knocks in walls, ceilings, or near the heater, sometimes your water heater sounds like a jet engine when it fires up or shuts off.
Why it matters: Repeated water hammer can loosen fittings, crack pipes, and lead to leaks behind walls.
What to do:
- Have the home's water pressure checked and set to the recommended 40-60 PSI range.
- Consider installing water hammer arrestors on problem lines.
- Secure loose, rattling pipes with proper supports and insulation.
5. Clicking or Ticking: Thermal Expansion
A water heater making a clicking noise or a ticking sound is usually one of the least alarming issues.
Common causes:
- Metal parts expand and contract as the heater warms up and cools down
- Check valves or heat traps opening and closing
- Pipes rubbing against framing as they move slightly
This kind of noise is often more annoying than dangerous. Adding pipe insulation or cushioned supports can quiet it. If ticking is new and accompanied by other symptoms (like poor hot water or leaks), have it checked out.
6. Humming or Vibrating: Loose Electric Elements
If your electric water heater makes noise that sounds like humming or vibration, the heating element may be slightly loose and vibrating as electricity flows through it.
Is it dangerous? Usually not immediately, but it can shorten the lifespan of the element.
What to do: Tightening or replacing the element is a relatively simple job for a pro. Any time you're working with electricity and water, it's safest to bring in expert help for a noisy water heater.
Why Is My Water Heater Making Noise When the Water Is Off?
If you hear banging, popping, or hissing even when nobody is using water:
- Sediment heating: The burner may still be running to maintain temperature, causing sediment to pop and crackle.
- Thermal expansion: Pipes and fittings may expand and contract as the heater cycles.
- Slow leaks: Drips onto hot surfaces can hiss or sizzle even without active water use.
Any new noise coming from your water heater when everything is "off" is worth paying attention to. It's often the first clue that repairs or maintenance are overdue.
When Noise Means It's Time to Replace the Water Heater
Not every loud hot water heater needs to be replaced, but sometimes a noisy unit is just the last straw on an aging system.
Consider replacement if:
- The heater is 10-12+ years old.
- You've flushed it multiple times, and the water heater noises keep coming back quickly.
- You see rust on the tank or discolored hot water.
- There are active leaks from the tank body (not just fittings).
- Repairs are starting to cost a significant percentage of a new unit.
At that point, exploring modern, efficient models and professional water heater replacement options often makes more financial sense than paying for repeated fixes.
Quick FAQ: Common Questions About Noisy Water Heaters
Why is my water heater making a loud noise?
Loud pops, booms, or rumblings are usually sediment. A water heater making a loud banging noise could also be water hammer. Both are fixable, but sediment should be addressed before it damages the tank or burner.
Should a water heater make noise?
Mild humming and gentle burner noise are normal. If you're wondering, "Should my water heater be making noise?" because you're hearing whistling, sharp banging, or constant hissing, that's not normal, have it inspected.
Why is my electric water heater making noise?
Electric units commonly hiss or hum when elements are failing or covered in scale. A noisy electric water heater might need the element tightened, cleaned, or replaced, and sometimes a full tank flush.
Why is my gas water heater making noise?
Roaring, rumbling, or whooshing sounds from a gas unit can be caused by sediment, restricted airflow, or burner issues. Any suspected gas problem is a "call a pro now" situation — don't ignore a gas water heater making noise.
Can you hear a hot water heater running?
Yes, you'll usually hear some operating noise. But if your hot water tank is making noise that you can hear throughout the house, or if it suddenly sounds like a kettle or jet engine, it's time to investigate.
DIY vs. Professional Help for Water Heater Noises
Generally safe homeowner tasks:
- Checking for obvious leaks or puddles around the heater
- Making sure valves are fully open (without forcing anything)
- Listening carefully to identify when and where noises happen
- Scheduling routine flushing and maintenance before problems get worse
Call a professional for:
- Any hissing, sizzling, or suspected gas leak
- Repeated banging, knocking, or "jet engine" sounds
- Older tanks (10+ years) are making new or worsening noises
- Electrical work on heating elements or controls
- Rust, corrosion, or leaks from the tank itself
A trained plumber who works on noisy water heaters every day can quickly tell the difference between "annoying but harmless" and "this needs attention today." That peace of mind alone is worth it.
Expert Water Heater Help When Yours Starts Making Noise
If your water heater is making noises like popping, hissing, banging, or whistling, it's your system's way of asking for help. Most problems start small: a little sediment, a loose part, or a minor pressure issue. Catch them early, and you protect your home, your budget, and your hot water supply.
When you're ready for a professional opinion, inspection, or upgrade, the licensed plumbers at Dalmatian Plumbing can help. We handle trusted water heater plumbers who work on all major brands and models, tank and tankless, from routine maintenance to full replacements.
Don't ignore that strange sound coming from your utility room. Contact Dalmatian Plumbing today for professional water heater services that keep your system running quietly, efficiently, and reliably.
