Water Heater Leaking From Top: What Should I Do?8 min read

A leaky water heater isn’t something to ignore. In my years of experience, getting on top of problems like this as soon as possible is really important! But what makes a water heater leak from the top, and what can you do about it?

I find that the most common culprits include old age, pressure relief valve problems, loose fittings, and rust. None of these things are particularly fun to deal with, I’ll admit! But the good news is that you might not need to replace the whole thing just yet.

Let’s take a look at the possible causes, and what you’ll need to do to fix it.

This article has been expert reviewed for accuracy by our very own plumber, Mark Longhurst. Mark has been a plumber for over 15 years and owns his own business, PipeSmart.

Why is your Water Heater leaking From the Top?

So, there are a few reasons why a water heater might leak from the top of the unit (as well as from the bottom). It can be something small, or it can be a pretty big problem depending on what the cause is and how early you’ve managed to catch the problem.

Old Age

Over the years, I’ve come across this several times. Old age is usually the problem for most issues with water heaters because they tend to develop leaks or small cracks. These can come about for a ton of reasons, including loose fittings, damage, and faulty components.

These defects may cause corrosion, and sediment build-up, and just general wear and tear. But ultimately, nothing lasts forever, and water heaters will eventually degrade. If you’ve moved into an older home, you might find that the water heater is pretty old too. 

Pressure Relief Valve Problems

Okay, so the job of a pressure relief valve is to regulate the adequate pressure of water, stopping the whole unit from getting too pressurized. It’s a vital piece of the puzzle that you need for the water heater to work correctly.

But if the pressure gets a bit too much within the heater tank, it will cause water to escape from the top. You might notice water dripping from the threads, and you’ll have to remove the valve to figure out what to do next.

Loose or Damaged Fittings

The older a water heater gets, the more likely the fittings are to become loose or damaged. It’s just one of those things that happens after a while. This can cause water to leak from the top or in other places around the unit.

To be honest, loose fittings are one of the easier problems to deal with. You can usually fix it just by replacing or tightening the connections, which is pretty simple.

Rust and Corrosion

The other problem that may come for your water heater is rust and corrosion. Corrosion can cause the metal of the tank to deteriorate over time. If it’s severe you may need to replace the whole thing, although that is obviously the worst-case scenario: you can remove rust from things like tools, but it’s harder to remove from something like a water tank.

To get technical for a second, there’s something called an anode rod inside a water heater. Anode rods are a cool and integral part of your water heater. It attracts corrosive elements in the water, which protects the whole thing from rusting or corroding.

The problem is that anode rods need replacing more often than water heaters. I usually find they need replacing at around five years or so. If the anode rod isn’t working properly, it can cause water to leak from the top.


Sometimes you might think that water is leaking from the top, but it’s actually just condensation. This happens if the temperature in the tank is much higher than the surrounding air, like a water bottle. This is common in other appliances too (for example dryers can be prone to this), and is usually nothing to worry about!

Still, having a plumber come and check it out can confirm if it’s just condensation, or if there’s something else at play.

Signs of a Leaking Water Heater

Okay, so I’ve gone through the most common causes. But how can you tell if your water heater is leaking from the top? There are a few pretty obvious signs.

Water Around the Base of the Unit

You might spot pools of water, damp spots, or water stains around the base of the unit. This can damage your flooring over time, so it’s good to catch it early. You might also notice water dripping from the fittings, or leaks on the sides.

Discoloured Water

If your water isn’t looking so healthy, it may be a sign that there is rust and corrosion. If your water is murky, discoloured, or yellowing, this means there’s a rust issue in there somewhere. The water may contain a high level of sediment build-up, and is (sadly) a sign that the whole thing may need to be replaced.

Strange Noises

All water heaters make noises sometimes, but new sounds may be the symptom of an issue. Popping or cracking sounds are worth watching out for, because that may mean there’s excessive sediment at the bottom of the tank that has hardened, causing the weird noise.

This is not just a problem because of leaks. It can actually mean that your water heater has to work harder, leading to expensive energy bills. Given the expensive cost of heating a house, I think that’s something to keep an eye on!

The tank should be drained every 6-12 months to prevent this. I know it’s tricky to remember but it’s worth it because it can prevent the sediment from hardening. You may need professional replacement if the sediment has already hardened.

As a general rule, if any appliance in your home whether it’s something like your boiler or even your dryer starts making a strange sound, it’s a warning sign!

Changes to Your Water

Lower water pressure may mean that your water heater tank or pipes have a leak somewhere.

You may also notice a sudden temperature drop. This means that the unit might be reaching the end of its lifespan.

Loose fittings can cause problems with water pressure, but it can also be caused by more severe problems like sediment build-up. It’s a good idea to get a plumber out to check on it in this case.

Higher Water Bills

Have you noticed a sudden increase in your water bill, even though you haven’t really changed your usage?

This could be a sign that there’s a leak somewhere. If your heater is wasting water, leaks, sediment build-up and other issues can cause your water to work harder. The quicker you get this fixed, the better for your budget.

As a professional plumber, I always recommend that my clients monitor their electricity bills. If there’s a sudden change in pricing, it may be because of your electricity company, or it may be because of a fault with your own appliances.

Mark Longhurst

how to fix a Water Heater That’s Leaking from the Top

At this point, you may be pretty certain that your water heater is leaking from the top, and you may be aware of what’s causing it. So what next?

There are a few DIY solutions you can try, but as always, only go for this if you feel comfortable; if you’re not sure you want to do it yourself, a plumber can do it properly.

Necessary Tools and Materials

Before you start, you’ll need the following:

Step 1: Turn Off the Unit

The first step is to disable the gas or electricity in the unit before you start troubleshooting. Safety is always the number one priority.

  • For gas heaters, switch the gas valve to the OFF position. The valve is located on the unit. Be sure the ball valve on the gas piping is turned at a 90-degree angle.
  • For electric heaters, turn the power off at the electrical panel. Find the two-pole breaker labeled “water heater” and switch it to OFF.

Step 2: Locate the Leak

Now that safety precautions are done, it’s time to turn the water back on and hunt for leaks.

The most common areas for a top water heater leak are:

Cold Water Inlet Valve

The cold water inlet valve is located directly over the water heater and will drip water onto the top of the unit.

Solution: If it leaks, attempt to tighten the nut holding the handle in place. Use a wrench, turning the nut counterclockwise.

Pipe Fittings

Inspect all the fittings and connections on the top of the unit. You may have a leak if you notice any corrosion, like rust or white powder.

Solution: If a pipe fitting is leaking water, try to tighten it with a wrench. Identify any signs of corrosion or rust, as these parts will need replacements.

Anode Rod Port

The anode rod is a long, thin rod that attracts corrosive water materials to prevent the tank from corroding. If it becomes damaged or isn’t replaced, water will leak from the top of the unit.

Solution: Leaks from the anode rod will require professional assistance, as it could indicate your tank is about to burst. In this case, you’re probably going to have to replace the whole thing.

The Expansion Tank

Many units have an expansion tank installed on top of them. The expansion tanks absorb excess hot water as a secondary safety measure. It can develop leaks from the threaded fittings, the tank, and the air valve.

Solution: First, confirm the source of the leak. If it’s the threaded fittings, remove the connection point and apply some thread sealer. If it’s leaking from the tank or the air valve, you’ll need to contact a professional, as the pressure in the unit needs to be adjusted and that’s a job for a plumber.

The Tank

If the tank has a crack or a tiny hole, you may notice water leaking from the top of the unit. This typically means the inside of the tank is corroded and needs to be replaced as soon as possible.

How to Replace the Temperature and Pressure Relief Valve

The T&P Relief Valve (temperature and pressure relief valve) is a safety feature that releases hot water if your unit exceeds the desired temperature or pressure limits. Depending on the model, it can be found on the heater’s side or top.

The T&P relief valve can leak from the base where it screws into the unit or from the piping connected to it.

The exact instructions to replace the T&P relief valve will vary depending on the unit, but here’s a general guide to give you a better idea of what to expect (remember, don’t attempt this unless you feel comfortable doing so and are experienced; otherwise get a professional plumber).

  1. Disable the cold water to the unit and gas or electricity. Close the shutoff valve on the cold water inlet line.
  2. Drain the water from the water heater until the water level is beneath the valve. Remember, the water will be very hot! To do this, attach a garden hose to the drain valve, open hot water at any faucet to relieve the pressure, and open the drain valve.
  3. Lift the lever on the T&P valve to release any residual pressure.
  4. If your unit has a discharge pipe, unscrew it by turning the pip counterclockwise.
  5. Unscrew the old valve from the unit after you’ve removed the discharge pipe. You will need a wrench to turn it counterclockwise.
  6. Next, wrap pipe-thread tape onto the discharge pipe’s threads. Screw it into the new valve and tighten it with a wrench. Be sure the T&P lever is closed.
  7. Afterward, open any hot water faucet in your home. Next, open the cold-water shutoff valve to the heater. Place a bucket under the discharge pipe and when you hear the tank fill with water, lift the pressure-release lever on the T&P valve.
  8. Once the water from the discharge pipe is a steady stream, close the pressure-release lever. After hot water goes through the faucet you opened earlier, you can shut off the tap.
  9. Lastly, power on the gas or electricity and relight the pilot light if necessary. Give the unit a few moments to reheat and inspect the valve again to ensure it isn’t leaking.

I found this awesome video tutorial on how to replace the pressure release valve:

Common Mistakes to Avoid

  • Don’t forget to turn off the power and water supply to the water heater before starting repairs. (This is really important!)
  • Don’t attempt to fix a leak from the pressure relief valve without first shutting off the cold water supply and opening a hot water faucet to relieve pressure.
  • Don’t use too much force when tightening fittings as it can cause damage to the tank or pipes.
  • Don’t forget to reattach the discharge pipe to the pressure relief valve after replacing it.

When to Call a Professional

Many causes of water heater leaks can be fixed with a bit of elbow grease and a little time. But there are some jobs that are best left to the professionals.

You might want to contact a plumber if:

  • You’re unsure of how to handle repairs
  • You’ve tried to fix it, but it’s still leaking
  • Your water heater is making weird noises like popping or hissing
  • The water heater is damaged beyond repair, or has corrosion/rust

Contact a professional at least once a year to check on your tank and the components, if you can. It’s usually recommended that you replace a water heater when it gets to around ten years, but really, this can vary depending on the model.

I’d recommend using a plumber that has been personally suggested to you, by a family member or a friend, so you know that they’re legit. If you don’t know anyone, Google reviews are a good place to check.

When to Replace Your Water Heater

The question of when your water heater needs to be replaced depends on a few factors: it’s not a black-and-white timeline. It depends on the maintenance schedule, age, water quality, and usage levels. The type of water also impacts the longevity of the water heater:

Type of Water HeaterAverage Lifespan
Traditional tank-type water heaters8–12 years
Tankless water heater18–20 years or more

With a little TLC, many water heaters can last longer than their expected lifespan, but it’s always a good idea to plan ahead for replacements. If you’re getting to the 8-year level with your tank-type water heater, it may be time to start saving for a new one. Same goes for the 15-year level for your tankless water heater.

It’s annoying when you have to replace big appliances like boilers, but you can plan ahead to take the sting out of the cost.

We always recommend to our clients that they book a Preventative Maintenance Schedule (PMS) for heaters and other plumbing devices. Having a plumber regularly check things out can make sure that you catch problems early, which can save you money in the long run.

Mark Longhurst

Water Heater Leaking from Top – Key Takeaways

There are a few reasons why your water heater may leak from the top:

  • Old age – nothing lasts forever, and it may just be time to buy a new water heater
  • Pressure relief valve problems – the pressure relief valve plays an important role, but may need adjusting
  • Loose or damaged fittings – this is the easiest problem to fix, as you just have to tighten up/replace the fittings in most cases
  • Rust and corrosion – once your water heater starts to get rusty, it may be time for a replacement
  • Condensation – what looks like a leak may actually just be harmless condensation

I’d say, if you can, get on top of the problem immediately. This should prevent further damage and minimize both your maintenance costs and your monthly bills!

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Hi, I'm Ed, and I run BuildFanatic! I enjoy providing the best possible information on a range of home improvement topics.

Mark Longhurst
Plumber at http://www.pipesmart.com.au/ | Website | + posts

Mark Longhurst is a professional plumber with over 15 years of experience, owns Pipesmart, and is our resident expert in all things plumbing.

Mark helps review plumbing-related articles for BuildFanatic to ensure we're providing our readers with the most accurate and updated advice.

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