9 Warning Signs Your Water Heater Is Going to Fail (And How to Fix It)

Is your water heater on its last leg?

Many homeowners overlook the warning signs of a failing water heater until it’s too late, leaving them with cold showers and unexpected repair bills.

In this guide, we’ll walk you through the 9 signs your water heater is going out so you can act before a complete breakdown. From odd noises to fluctuating temperatures, we’ll break down the red flags you need to watch for.

Plus, we’ll share practical tips to help you decide when it’s time to replace the unit—saving you from unexpected cold showers and expensive repairs, and even potential water damage.

By the end, you’ll be equipped to make informed decisions about troubleshooting, repairs or replacements, saving you time, money, and frustration. Don’t let a failing water heater catch you off guard—read on to learn what to watch for!

Typical Signs Your Water Heater Is Going Out

Here, you will learn how to identify key warning signs that your hot water heater is failing and when it’s time to replace it. We’ll cover various causes of water heater failure, including age, rust, unusual noises, leaks, and insufficient hot water. Other factors, such as frequent repairs, rising energy bills, structural deformations, and the effects of flooding, will also be discussed.

1. Water Heater Is Old

If your water heater is over 10 years old, it’s likely nearing the end of its lifespan. Most tank-type models start showing signs of failure after a decade, such as reduced hot water supply, lower energy efficiency, or higher utility bills.

To check the age of your unit, follow these steps:

• Locate the Manufacturer’s Sticker: Look for the rating plate or sticker on the unit, usually near the top. It will list details like the serial number, model, fuel type, and manufacture date.
• Decode the Serial Number: The serial number often includes the manufacture date, but the format varies by brand. Here’s how to decode it for three popular manufacturers:
  • AO Smith: Example serial number 1803**** means the unit was built in 2018 (18 = year), week 3 (03 = week).
  • Rheem: Example serial number 1015**** means October (10 = month) 2015 (15 = year).
  • Bradford White: Example serial number MA**** means January (A = month) 2015 (M = year).
    • Months: A = January, B = February, … M = December.
    • Years: A = 1984/2004, B = 1985/2005, … T = 1999/2019, W = 2000, X = 2001, Y = 2002, Z = 2003.

If you’re unsure, check the unit’s manual or visit the manufacturer’s website for more details.

How Long Do Water Heaters Last?

Most tank-style water heaters come with a 6-year warranty and typically last 10 to 15 years. However, their lifespan depends on several factors, including the quality of installation, how well they’re maintained, the quality of your water, and how heavily they’re used. Once your unit reaches the 10-year mark, you’ll likely notice signs of wear and tear—components may start failing, efficiency can drop, and heating times often increase.

If you’re looking for a longer-lasting solution, consider upgrading to a tankless water heater. These units are designed to provide on-demand heating and, with proper maintenance, can last over 20 years. Top brands like Rinnai and Takagi even offer 15-year warranties on their premium models, making them a reliable and cost-effective choice for the long term.

2. Corrosion and Rusty Water

Rusty or discolored water from the faucet is one of the first signs of a failing water heater.

Corrosion in a water heater often shows up as rust on the exterior or discolored, rusty hot water caused by internal damage. While these issues might seem minor at first, they can quickly escalate into leaks or even complete system failure if left unchecked.

Most tank-type models are built with protective features like a glass liner and an anode rod to combat corrosion. However, over time, these safeguards wear down, leaving the tank exposed. Cracks in the glass liner—caused by manufacturing flaws, thermal stress, or chemical reactions—can allow water to seep into the metal tank, leading to rust and eventual failure.

Here are some tips to help your water heater last longer:

Tip 1: Inspect the anode rod annually (or as recommended by the manufacturer) and replace it if it’s worn out. This simple step can significantly slow down corrosion. To check for internal corrosion, attach a garden hose to the drain valve at the bottom of the unit and drain a few gallons of water. If the water looks rusty or has a metallic taste, corrosion may already be underway.

Tip 2: Drain and flush the water heater yearly to remove mineral deposits and sediment buildup that can contribute to internal damage.

Tip 3: Prevent corrosion by using dielectric fittings made of galvanized steel with inner plastic tubing. These fittings help reduce the risk of electrical corrosion between metal components, extending the lifespan of your water heater.

Once corrosion sets in, it spreads quickly and can lead to leaks or complete tank failure. While some components may be replaceable, addressing corrosion usually involves replacing the entire water heater to avoid further damage and costly repairs. Proceed with caution and consider replacing the unit if corrosion is widespread.

3. Leaks That Cannot Be Fixed

Not all leaks are created equal but are a clear sign of failing water heater elements. While minor drips from plumbing or loose connections can often be repaired, some leaks are difficult or impossible to fix. These are typically caused by serious issues like cracks or fractures in the tank itself.

The first sign of a major leak is usually water pooling under the unit. If the unit is located in an attic or near living spaces, a large leak can lead to significant property damage. For example, a fractured or cracked tank can release a substantial amount of water, causing harm to floors, walls, and belongings.

Leaks often occur due to corrosion or mechanical stress over time. Initially, fractures may be small, but constant exposure to thermal stress can cause them to worsen. If you notice a leak caused by these issues, it’s crucial to replace the device immediately.

Ignoring leaks can lead to more than just water damage. Over time, standing water can promote the growth of mold and mildew, which pose health risks to you and your family. To avoid these problems, address leaks as soon as they appear and consider replacing your heater if the damage is beyond repair.

4. Bulging Water Heater and Excessive Internal Pressure

Bulging is a serious problem caused by excessive pressure inside the tank or blockages, indicating that your water heater is going to fail. If you notice this issue, it’s crucial to address it immediately, as it often signals irreversible damage.

Common symptoms include:

• Deformations (e.g., bent nipples or dislocated flue pipes).
• Leaks.

A deformed water heater cannot be repaired and must be replaced. Prevent this by installing the unit properly, including an expansion tank.

If left untreated, the water heater may burst.

5. Heavy Sediment Buildup and Strange Noises

If your water heater is underperforming, making strange noises (rumbling, knocking, popping), or taking too long to heat water, inspect it for sediment buildup.

Hard water causes mineral deposits to form at the bottom of the tank, which insulates the heat source from the water and reduces efficiency. Over time, this can lead to decreased performance and potentially cause your water heater to go bad.

To prevent sediment buildup: Flush the unit regularly, as recommended by manufacturers and experts.

6. Insufficient Hot Water

A lack of hot water in your kitchen or bathroom is one of the most obvious signs of water heater failure.

If you’ve noticed that your hot water supply isn’t as strong as it used to be, your heater might be losing efficiency. This could be due to sediment buildup, aging components, or general wear and tear affecting its performance.

For example, if your showers are becoming shorter or you need to wait longer between uses, it’s a clear sign that the unit isn’t functioning properly. Deciding when to replace a water heater is often driven by this decline in performance, as a new unit can restore the consistent and reliable hot water supply you’re accustomed to.

7. Frequent Repairs

When the cost of repairs starts to add up, it might be more economical to replace the unit altogether. Frequent issues are a strong indicator that the water heater is on its last legs.

For instance, if you’ve had to call a technician multiple times in the past year for various problems, the cumulative cost of repairs could approach the cost of a new unit. Repeated repairs on an aging system are often a sign that it’s nearing the end of its lifespan. Instead of pouring money into a failing system, investing in a new, more efficient model is a smarter choice. This not only provides peace of mind but also ensures long-term savings and reliable performance.

8. Rising Energy Bills

Aging water heaters can become less efficient, leading to increased energy consumption and higher utility bills. If you notice a significant spike in your energy costs, your heater could be the culprit. Newer models are designed to be more energy-efficient, which can save you money in the long run. The right timing for replacement is often influenced by this economic factor, as the initial investment in a new unit can be offset by lower operating costs over time.

9. Flooding

If your basement or the area around your water heater has been flooded and it has been submerged for any length of time, it is crucial to consider replacing it. Flooding can damage the internal components of the unit, including the insulation and electrical parts, making it unsafe to operate. Even if the heater seems to be working fine after drying out, hidden damage could lead to future failures.

Dealing with Water Heater Failure

Every water heater will experience issues over time, and many factors contribute to its eventual failure. Paying attention to the warning signs and knowing when to replace a water heater can save you from unexpected inconveniences and potential damage to your home.

Proactively replacing it before a catastrophic failure can ensure you always have a reliable supply of hot water. It also helps you avoid costly repairs and prevent damages.

While we’ve covered some of the most common causes, it’s important to remember that regular maintenance is key to prolonging your unit’s lifespan.

If you notice signs that your water heater is going out and is beyond repair, as discussed, it’s best to reach out to a licensed technician for a replacement. Taking action early can save you from further inconvenience and prevent costly damage down the line.