Why Your Water Heater’s Pressure Relief Valve Is Leaking — And What You Can Do About It

If you’ve ever spotted water dripping down the side of your water heater or found a small puddle near the base, you’re not alone. It can be unsettling and messy. One of the most common culprits behind this kind of leak is the pressure relief valve.

I’ve had friends call me in a panic, thinking their entire water heater was busted, when it was actually something pretty small, but still important to fix. Let me walk you through exactly what’s going on and what you should do next.

Water Heater Pressure Relief Valve Leaking

A leaking pressure relief valve usually means there’s too much pressure or heat inside the tank, or the valve itself is worn out. This valve is a safety feature, so if it’s leaking, it’s doing its job, but it still needs attention.

Why Is My Water Heater Leaking From the Top?

If water is coming from the top of your water heater, there’s a high chance the temperature and pressure (T&P) relief valve is involved. This valve is designed to release excess pressure if the tank’s temperature or pressure gets too high. It’s usually located near the top of the tank, with a pipe running down the side to safely direct any discharge.

1. Check the Source of the Leak

Start by drying off the area and watching where the water appears. If the drip is coming from the pipe connected to the valve or the valve itself, you’re likely dealing with a T&P valve issue. Don’t confuse this with condensation or a leak from the cold-water inlet, which can look similar.

2. Understand the Function of the Valve

This valve is a safety mechanism. It opens automatically when the internal pressure exceeds a certain limit, typically around 150 psi or when temperatures reach 210°F. When working properly, it prevents the tank from exploding under pressure. So a little dripping occasionally could mean it’s just doing its job. But continuous leaking? That’s not normal.

3. Why It’s Often Misunderstood

A friend of mine once replaced his entire water heater because he noticed water dripping from the top and assumed the tank was cracked. When I stopped by to take a look, it turned out to be a faulty T&P valve, a $20 part. He spent over $900 on a new unit when a simple fix could’ve saved the day. That’s why identifying the real source of a leak matters more than you might think.

4. Don’t Ignore Repeated Drips

If you notice steady dripping from the valve pipe or water pooling around the tank, it’s time to take action. Ignoring it can lead to rust, corrosion, or even a bigger failure down the road. It’s always better to address these signs early, especially when it could be something as minor as tightening or replacing a valve.

Common Causes of a Leaking Pressure Relief Valve

When a pressure relief valve starts leaking, most people assume it’s broken, but that’s not always the case. Sometimes, it’s responding exactly the way it should to protect your water heater. Understanding the actual cause behind the leak can save you a lot of money and stress.

High Pressure Inside the Tank

One of the most common reasons a pressure relief valve starts leaking is that the pressure inside the tank is too high. Water heaters are designed to operate within a specific range, usually no more than 150 psi. If the internal pressure exceeds this, the valve will release water to bring the pressure down and prevent potential damage or even an explosion. According to the Department of Energy’s Building America guideline, all water heaters must be provided with approved pressure‑and‑temperature relief valves alongside an expansion tank when necessary.

High pressure can happen for a few reasons. Sometimes, the thermostat is set too high, which causes the water to heat beyond safe levels. Other times, a faulty expansion tank or a malfunctioning pressure regulator in the home’s plumbing system can cause the pressure to climb. Either way, the valve is acting as a safety net, but repeated leaking means the root issue still needs to be fixed.

Faulty or Worn-Out Valve

Even if the pressure inside the tank is perfectly normal, the valve itself can still fail. Like most parts in a water heater, the T&P valve can wear out over time. Sediment buildup, mineral deposits from hard water, or corrosion inside the valve can prevent it from sealing properly. When that happens, even a small gap in the valve seat can cause water to drip out consistently.

This is more common in older water heaters, especially if regular maintenance like flushing the tank hasn’t been done. Rust and debris can work their way into the valve and interfere with its function. In this case, the valve isn’t relieving pressure; it’s just leaking due to age or wear.

Improper Installation

In some cases, the valve was never installed correctly in the first place. A loose fitting, lack of plumber’s tape, or cross-threading can all lead to slow leaks from the joint. This often happens in newer units where the valve was installed in a rush or by someone who didn’t tighten it properly. The valve might look fine on the surface, but it can still leak if it’s not fully sealed.

Incorrect installation can also make the valve more likely to leak under normal conditions, simply because the water has a pathway to escape. If you’ve recently had your heater installed or moved, this might be the cause.

Thermal Expansion and No Expansion Tank

Every time water heats up, it expands. In a closed plumbing system without an expansion tank, there’s nowhere for that extra volume to go. As a result, pressure builds up inside the tank. The T&P valve then opens to release this pressure, which can look like a leak, but it’s actually just doing what it was designed for.

An expansion tank helps absorb that extra volume of water and reduces the load on the pressure relief valve. If your home doesn’t have one, or the existing expansion tank has failed, your pressure valve will have to work overtime, which can lead to constant dripping.

Mineral Buildup and Sediment

Over time, minerals in the water, especially in areas with hard water, can build up inside the tank and the valve. This sediment can cause the valve to stick open or create a poor seal. Even a small layer of buildup on the valve seat can allow water to leak out slowly.

This is one of the quieter causes of a leak. You might not notice it right away because it starts with just a few drips. But over weeks or months, the buildup worsens, and the leak becomes steady. Regular maintenance, like flushing the tank, can help prevent this issue.

When You Should Worry

Not all leaks mean something is dangerously wrong, but ignoring them can lead to damage or higher repair bills later on. If the valve is constantly dripping, spraying, or showing signs of rust, it’s time to investigate further. A one-time release of water might be normal, especially after a heavy day of hot water use, but consistent leaking should never be ignored.

Whether the cause is pressure, installation, or a failing part, getting to the root of the issue is the only way to fix it for good. And in most cases, once the cause is clear, the solution is a lot simpler than you might expect

What to Do If You Notice a Leak

Spotting a leak near your water heater can make anyone uneasy, but don’t panic. A leaking pressure relief valve is often a manageable problem, as long as you handle it the right way. Here’s a clear, step-by-step guide to help you stay safe and figure out your next move.

Turn Off the Power and Water Supply

The first thing to do is shut off the power to your water heater. If it’s electric, turn off the breaker. If it’s gas, set the thermostat to “pilot” mode. This keeps the tank from heating while you inspect the problem.

Next, shut off the cold-water supply valve going into the top of the heater. This prevents more water from filling the tank and making the leak worse.

Let the Tank Cool Down

Water inside a heater can reach temperatures over 120°F, even hotter if the thermostat is set too high. Letting the tank cool for at least 30–60 minutes before touching the valve or any fittings is smart. This reduces the risk of burns and pressure buildup.

Inspect the Valve and Discharge Pipe

Now, look closely at the T&P valve and the pipe attached to it. You’re checking for:

• Visible cracks or corrosion
  
• Loose fittings or threads
  
• Continuous dripping or sudden discharge
  
• Signs of mineral deposits or rust
  

Sometimes, a valve leaks just because it’s not tightened fully or has mineral debris in the seat. In rare cases, the leak may be from a nearby pipe joint, not the valve at all.

Try a Gentle Reset (If Safe)

If the valve looks clean and undamaged, try lifting and releasing the valve’s test lever briefly. This can sometimes flush out sediment. But if water sprays forcefully or doesn’t stop dripping afterward, the valve likely needs to be replaced.

Call a Professional if…

• The valve is corroded, rusty, or stuck
  
• Water keeps leaking even after a reset
  
• You’re unsure whether the leak is dangerous
  
• You don’t have plumbing tools or experience
  

When to Repair vs Replace, Quick Guide

Here’s a quick comparison to help you decide what step to take next:

Acting quickly protects your home and avoids water damage. Even a small leak can lead to major issues if left alone too long.

Repair or Replace the Water Heater?

Once you’ve confirmed the pressure relief valve is leaking, the big question becomes, should you just replace the valve or go ahead and replace the whole water heater? The answer depends on a few key factors, like the age of your unit, how often it’s been leaking, and what kind of shape the rest of the tank is in.

When a Simple Repair Is Enough

In many cases, especially if the water heater is under 8–10 years old and the leak just started, you’re likely dealing with a worn-out valve. Replacing the valve is a straightforward and affordable fix.

Here’s when a repair makes sense:

• The leak is steady but not severe
  
• The tank is in otherwise good condition
  
• You don’t see any rust, corrosion, or damage around the base
  
• It’s the first time you’ve had an issue with the valve
  

Most plumbers can replace a T&P valve in under an hour, and the part itself usually costs less than $30. That’s a small investment to keep your system running safely.

When It’s Time for a Replacement

There are some situations where replacing the entire unit is a smarter move, especially if you’ve had ongoing issues or the tank is nearing the end of its lifespan.

You should think about a full replacement if:

• Your water heater is over 10–12 years old
  
• The tank shows signs of rust or leaking from the bottom
  
• You’ve had multiple valve or heating issues recently
  
• You want to upgrade to a more efficient or tankless model
  

My friend had an older unit that kept leaking from the valve every few months, even after two replacements. It turned out the internal lining was deteriorating, causing pressure fluctuations. Replacing the unit not only stopped the problem but also cut his energy bill by 15%.

Factor in Efficiency and Long-Term Costs

Older water heaters can also cost more to run each month. A newer model, especially an energy-efficient one, may pay for itself over time. And if your current heater can’t keep up with your household’s hot water demand, an upgrade could improve your comfort and lower frustration.

In short, if the tank is young and strong, fix the valve. But if the heater is aging or showing deeper problems, a new unit may be the better long-term solution.

What Is a Pressure Relief Valve and What Does It Do?

Every water heater has a built-in safety mechanism called the temperature and pressure relief valve, often shortened to the T&P valve. This small but critical component protects your water heater and your home from dangerous pressure buildup inside the tank.

The Basic Function of the Valve

When water heats up, it expands. That expansion increases the pressure inside the tank. If there’s no way to release this pressure, it can reach unsafe levels. The T&P valve steps in by opening slightly when the internal pressure hits around 150 psi or when temperatures go above 210°F. This lets out just enough water to stabilize the system and prevent damage or worse, a burst tank.

The valve is typically located near the top or side of the water heater, with a discharge pipe running down to the floor. If it does its job, you might see water dripping from this pipe occasionally. That’s perfectly normal after heavy use, like multiple showers in a row. But ongoing leaking isn’t normal, and it’s something worth checking.

Safety First

This valve isn’t just a convenience; it’s a major safety device. If pressure isn’t released, your tank can fail under pressure, creating a serious hazard. The T&P valve exists to keep that from happening. It’s the last line of defense between normal operation and a potentially dangerous situation.

Some homeowners are tempted to cap the pipe or remove the valve if it’s leaking. That’s never safe. Doing so disables the system’s pressure relief and can cause serious consequences down the road.

Why It Deserves Regular Attention

Because this valve usually stays untouched for years, it’s easy to forget it’s there. But like any part exposed to heat, pressure, and water minerals, it can wear out or get stuck. Regular inspections, especially during annual water heater maintenance, can help catch problems early. A functioning T&P valve is a sign your system is safe. A faulty one is like a ticking time bomb.

This small component plays a big role in protecting your home. Understanding how it works and paying attention to the signs when something goes wrong can save you from bigger issues in the future.

Final Thoughts

A leaking pressure relief valve might seem small, but it’s your water heater’s way of telling you something’s not right. Whether it’s excess pressure, sediment buildup, or just an old valve showing its age, catching the issue early makes all the difference.

If you’re unsure about what’s causing the leak or how to fix it, don’t guess; get it checked. A quick repair now can save you from bigger, costlier problems later.

Need Reliable Water Heater Repair Near You?

If your pressure relief valve is leaking or your water heater just isn’t working right, Richmond Air Heating & Cooling is here to help. We proudly serve Richmond, VA, and nearby areas with fast, honest, and expert plumbing support.

From small valve fixes to full water heater replacements, our licensed technicians get the job done right, the first time.

Call us today or book a service online to get your hot water running safely and smoothly again.

FAQs About Leaking Water Heater Pressure Relief Valves

1. Is it normal for the pressure relief valve to leak a little?
   A small drip during high-pressure situations (like heavy hot water use) can be normal. But if the leak continues for hours or days, that usually signals a worn or faulty valve that needs to be checked.
2. Can I plug or cap the valve to stop the leak?
   No, never cap or block a pressure relief valve. It’s a safety device. Blocking it could cause dangerous pressure buildup inside the tank and lead to serious damage or even an explosion.
3. How often should the pressure relief valve be replaced?
   Typically, every 3 to 5 years is a good rule of thumb, or sooner if you notice leaking, rust, or if the valve doesn’t open and close smoothly during a test.
4. How do I test the valve to make sure it works?
   Lift the small lever on the valve carefully. You should hear water release through the discharge pipe. If nothing happens or it doesn’t close properly afterward, the valve may be bad.
5. Can a leaking valve cause my water heater to fail?
   If ignored, yes. Constant leaking can lead to rust, internal damage, or even flooding. Fixing the issue early helps extend the life of your heater and avoid expensive repairs later.

If you’re unsure or want help, Richmond Air is always ready to take care of it safely and professionally.