You’re sitting there just enjoying a quiet evening at home when, all of a sudden, you hear it – a pop, bang, or even a strangely persistent rumble coming from the direction of your utility closet or garage. It’s your water heater, and it’s suddenly far more vocal than it should be. Understandably, your first question is: “Why is my water heater making noise?” Followed, quite obviously, by your second: “Do I need to worry?”

Water heaters are designed to operate quietly in the background. So, if yours has all of a sudden become the loudest appliance in the house, it’s likely a sign that something isn’t quite right. And while some sounds are relatively harmless, others can be early signs of deeper issues that might need to be addressed. 

Knowing the difference can save you from unnecessary worry or a major repair bill down the line. Below, we’ll break down what the noises typically mean, what causes them, and when it’s time to call in the experts at George Salet Plumbing.

What’s That Sound? Common Water Heater Noises Explained

First of all, your concern about your suddenly noisy water heater is completely valid. A loud water heater isn’t just loud – it’s also your system’s way of telling you something is wrong. Here are a few of the most common sounds we hear homeowners report and what they mean: 

Popping or Rumbling

If your water heater sounds like it’s boiling a pot of rocks, you’re more than likely dealing with some sediment buildup. Over time, minerals and debris from your water supply settle at the bottom of the tank. When the burner heats the water trapped in this built-up sediment, it causes a bubbling or popping sound as the water tries to escape. 

Should you worry about it? Yes. Not only does sediment reduce heating efficiency, but it can also cause your tank to overheat and shorten its lifespan. In extreme cases, it may even damage the tank lining. This is a common issue if you’re in an area with hard water, like much of the Bay Area. Luckily, regular water heater flushing can usually resolve it. 

Screeching or Whistling

When you start hearing a high-pitched sound, like screeching or even whistling, from your water heater, it’s usually a result of restricted airflow. The restriction is typically due to a partially closed valve or buildup in the water line, which forces water through a small opening at high pressure. This results in that tea kettle whistle-like sound that can be quite annoying. 

Is it bad to hear that sort of sound? Well, potentially. A screeching noise could possibly be fixed by adjusting the inlet or outlet valve. However, if left unchecked, it could increase the strain on your system. In some cases, it could also point to a failing pressure relief valve, which could be a serious safety concern if left malfunctioning. 

Banging or Knocking

This alarming sound, often called “water hammer,” is caused when water moving quickly through your pipes suddenly stops, often due to a closing valve or faucet. The following pressure wave then travels through your plumbing, creating a loud bang or thud. 

Is this an issue? Yes, absolutely. Repeated water hammering can weaken joints, loosen fittings, or even cause pipe damage over time. If your home doesn’t have water hammer arrestors (or if they’ve failed), a plumber can install or replace them to solve the problem.

Ticking or Tapping

Ticking sounds are, for the most part, harmless and often linked to thermal expansion. This is where your water heater’s pipes or metal components expand and contract as the water heats and cools. Sometimes, it’s the sound of the water meter or check valve working as they are meant to do. 

That being said, should you worry if you hear this weird noise from your water heater? Usually not. This kind of sound is typically more annoying than cause for concern. However, if you’re finding it accompanied by other common water heater problems like inconsistent water temperature or strange smells, it could be worth investigating. 

When Should You Call in the Professionals? 

Not every noise means danger for you and your home, but it’s always better to be safe than sorry. This is especially true when dealing with gas-powered or electric water heaters. Here are a few signs that might indicate it’s time to bring in a licensed professional: 

• The noise continues even after flushing the tank
• You notice leaking, pooling water, or corrosion
• There’s a rotten egg smell (a sign of bacterial growth or a gas issue)
• The hot water runs out faster than usual or turns lukewarm quickly
• You hear bangs or booms that shake your pipes

Don’t Ignore a Noisy Water Heater—Know When to Act

Your water heater is one of the hardest-working systems in your home. When it starts to make unusual sounds, it’s trying to get your attention, so don’t ignore it. The best thing you can do is stay informed, perform regular maintenance, and know when to call in the pros.

Whether you need a quick repair, routine service, or a full water heater replacement, the team at George Salet Plumbing is ready to help.

Get Water Heater Repair from George Salet Plumbing in San Francisco, CA

If your water heater is making strange noises or showing signs of wear, it’s time to take action. 

Call George Salet Plumbing today at (415) 234-0733 for expert plumbing service in San Francisco, Daly City, Pacifica, and the surrounding Bay Area. We’ve been keeping local homes comfortable and quiet since 1979.