Is Your Water Heater Leaking from the Bottom? Here’s What You Should Do8 min read

A water heater is one of the most critical appliances in your home, impacting everything from your shower to your kitchen sink, but it can also cause significant damage if it malfunctions: believe me, you don’t want to have to deal with water damage if your water starts to leak from the bottom.

Water heaters can leak from sediment build-up, rust, loose parts, and old age. Turning off the power and the water supply so you can easily check for cracks, leaks, and damage is essential. I always say, if you feel nervous about dealing with this sort of stuff or the tank is beyond repair, it’s best to hire a professional.

I’ve got some good news, though. You don’t need to panic if your water heater has sprung a leak. A water leak is caused by a few common issues that can be resolved easily and swiftly. Let’s take a look at how to troubleshoot a leaking water heater.

This article has been expert reviewed by Mark Longhurst, a plumber with over 15 years of experience and owner of Pipe Smart. We take reliable information seriously, so look out for expert quotes in this article.

Why Is Your Water Heater Leaking from the Bottom?

There are actually a few factors that can cause water to heat from the base of the unit (as well as from the top). Problems like excessive sediment, corrosion, loose components, and age are all pretty common reasons for a leak. You’ll need to figure out what the problem is so you can fix it (or call a plumber for help).

Sediment Build-Up

A common cause of water heater leaks is sediment build-up. I’ve seen this a few times in water heaters, as it’s pretty common for minerals, debris, and sediment to accumulate at the bottom of the tank over time. This can cause corrosion and even damage.

Sediment build-up is a common cause of water heater leaks. Minerals, debris, and sediment can accumulate at the bottom of the tank over time, causing corrosion and eventual damage to the tank. You can’t stop this, although you can reduce it by regular flushing out – I’ll talk a little more about this later.


As a tank begins to age, the metal starts to corrode from exposure to water, oxygen, and minerals. This can cause tiny holes in the base of the unit, which means it may need repairing or even replacing in the worst case.

Personally, corrosion is difficult to deal with at home, and I’d really recommend calling a professional in this instance. Corrosion avoidance is key, and you need to pick a water heater made from materials like enamel-lined carbon steel, which is excellent at preventing corrosion.

Mark Longhurst

Loose Drain Valve

Water tanks have several connections and fittings, including the drain valve. The drain valve is a type of valve that can be found right at the lowest part of the tank. Its job is to drain out excessive amounts of water, or elements in the water like sediment. 

This, like the rest of the tank, can corrode over time and become loose or damaged. In my experience, this is a weak spot that can be prone to problems.

Faulty Tank

Unfortunately, water heaters don’t last forever. Regular wear and tear can cause problems, especially in older heaters. As much as I love to repair appliances where possible, typically, you’ll need to replace them. If you’ve just moved, you might find that older houses may have older appliances that need to be upgraded.

This involves contacting the manufacturer or the supplier: your water heater may still be under warranty, and it’s always worth talking to sales engineer services for help.

Signs Your Water Heater is Leaking

So, how can you tell if your water heater is leaking? In my experience, there are a few telltale signs that are dead giveaways.

Puddles of Water Around the Base of the Heater

This is the most obvious sign: puddles of water may start to pool around the bottom of the water heater, which means there has to be a leak somewhere. You might notice small damp spots or even drips of water coming out of the heater itself.

If you do spot this, you need to temporarily stop the water supply from entering the water heater and call for a professional service to help. They’ll be able to advise you on what to do next.

Rust or Corrosion on the Bottom of the Heater

You may also notice some rust spots or corrosion on the bottom of the unit, or if not, you might spot rust on the top or around the connections and valves.

Corrosion causes the metal to weaken over time, wearing away, which may eventually lead to holes in the tank and the fittings.

I’ve noticed that a common cause is a failing anode rod: this is a metal component that sits inside the tank to prevent corrosion. If this thing starts to rust, that’s going to cause some issues. I’ve seen this a few times over the years.

Water Stains or Damage on Floors or Walls Near the Heater

You might also see water stains or damage to nearby surfaces. In damp spaces, mold starts to form, so that’s a giveaway. You may also see uneven flooring or stains on the floor.

If this is the case, you need to take action quickly. Otherwise, you might find yourself with a hefty maintenance bill.

How to Troubleshoot a Water Heater That’s Leaking From the Bottom

So, you’ve figured out that your water heater is definitely leaking. Now is the time to act fast to save the unit or at least avoid the extra bills that come with damaged flooring.

Here’s what I’d recommend you do next:

Turn Off the Water and Power Supply

This is the most important step for your safety. Before you dig out your tool kit, turn off both the power and the water supply to your heater.

To turn the power off, find the circuit breaker that controls the water heater and switch it off. (For gas water heaters, you’ll need to turn the gas control valve to ‘pilot’).

You can stop the water supply by shutting off the valve near the unit. 

This is a really crucial first step for your own safety, so don’t skip it.

Drain the Tank Completely

Draining the tank sounds like a daunting task, but it’s actually pretty straightforward. Each unit will have slightly different instructions, and you should check the manufacturers’ website for accurate information. Some of the most common brands include Rheem, AO Smith, and Whirlpool.

Generally speaking, though, here’s how the draining process goes:

  1. Connect a hose: Find the drain valve at the base of the tank and attach a garden hose. Ensure the other end of the hose is in a safe location where the water can drain without causing issues.
  2. Open the valve: Slowly open the drain valve to begin draining the tank. The water may be hot, so be careful not to burn yourself.
  3. Drain the tank: Allow the water to drain completely from the tank. Depending on the size of the tank, this may take several minutes to an hour.
  4. Flush the tank: Once empty, turn on the cold water supply valve for a few seconds to flush any remaining sediment or debris from the bottom. Then, turn off the valve.
  5. Close the valve: Close the drain valve and remove the hose.

Here’s a useful video I found that you might want to check out:

That’s about it. Once you’ve done that, you can move on to the next step.

Inspect the Bottom of the Tank for Damage

Once the tank is drained and flushed, you can inspect it for damage. Look around the base of the unit and the tank for any visible leaks. It’s wise to check the connections, fittings, and pipes to see if they’re loose. In my experience, these little loose areas can cause real issues.

If you notice any signs of rust, corrosion, or leaks, you may have found the culprit behind the leak.

Repair the Damage or Replace the Tank

A replacement is, of course, a last resort: it’s expensive to replace the whole tank, and you might be able to repair the unit with a patch kit or some epoxy.

I will say, however, that this completely depends on the manufacturer: you need to follow their instructions closely, otherwise any repairs might not work.

Sometimes, though, the damage is just too much. If the damage is severe or the unit is old, it may be necessary to replace the water heater. It sucks, but it does happen from time to time.

I’d recommend calling a licensed plumber to figure out the best size and type of water heater for your space. A professional will be able to take care of everything for you.

Refill the Tank and Test for Leaks

If your water tank is still usable and you’ve attempted a fix, now is the time to refill the tank and test it out.

  1. Turn on the water supply: Open the cold water supply valve at the top of the tank and allow the tank to fill. Check for any leaks or issues with the water supply connection.
  2. Turn on the power supply: Open the dedicated circuit breaker for the water heater. This will allow you to check if there’s a problem with a faulty electrical circuit.
  3. Wait for the water to heat: Depending on the tank’s size and the incoming water’s temperature, it may take several hours for the water to heat up to the desired temperature. Check the manufacturer’s instructions for recommended wait times.
  4. Observe for leaks: Check for leaks or drips around the tank or connections once the water is heated. If you notice any leaks, turn off the power and water supply and contact a licensed plumber to address the issue.
  5. Monitor the tank: Keep an eye on the water heater tank over the next few days to ensure no further leaks or issues. If you notice any problems, contact a licensed plumber for assistance.

Safety Tips to Keep in Mind

When dealing with water heater issues, you need to keep yourself safe.

  • Turn off the power supply: Before attempting any repairs or replacements, turn off the power supply to the water heater by shutting off the circuit breaker dedicated for the water heater. This will prevent the risk of electrical shock.
  • Turn off the water supply: Shut off the water supply to the water heater to prevent additional water from entering the tank.
  • Allow time for the water to cool down: If you need to drain the tank or work on the water heater, wait for the water to cool down before starting. Hot water can cause severe burns or scalding.
  • Use protective gear: Wear protective equipment, such as gloves and eye protection, when working on the water heater. This will help protect you from any hot water or debris that may come out of the tank.

I know some of these steps may take time, particularly allowing time for the water to cool down, but really, you do need to follow them to stay safe. Having been on the receiving end of scalding from a water heater, I can tell you it’s just not worth the risk.

How to Prevent Leaks

Having to deal with a water leak is really frustrating. Leaks can impact your unit, lead to higher energy bills, and damage your home. It’s an all-round bad situation. There are a few things I would recommend that you do to help prevent it from happening again in the future:

Regular Maintenance

Schedule annual maintenance check-ups with a licensed plumber to inspect the tank, anode rod, and other parts for damage. The plumber will identify problems before they become severe. Honestly, this is absolutely worth doing and can save you money in the long run: I’ve repaired or replaced appliances in the past that could have been saved if I’d been called in earlier.

Flushing the Tank

Regularly flushing the tank will remove sediment and mineral build-up. Most professionals recommend flushing the tank every six to twelve months, depending on the unit. Sediment can cause damage, so you want to reduce it as much as you can.

You don’t need to be a plumber to do this. I’d just suggest checking out the manufacturer’s instructions to make sure you’re doing it properly for your own safety.

Inspect for Corrosion

Identifying signs of corrosion and rust will help prevent further damage to your unit. This can be part of your routine maintenance schedule to ensure your water heater’s condition. The last thing you want is for severe rust to form, as you might have to replace the whole thing. (I know this from experience with my own water heater: severe rust just isn’t fixable in a lot of cases.)

Check for Loose Connections

Inspecting the pipes, fittings, and connections will help you identify leaks before they happen. This is another consideration to add to your maintenance schedule.

Address Minor Repairs Promptly

If you notice any tiny holes, cracks, or loose fittings, it’s essential that this should be properly assessed and handled by a professional. This will prevent minor issues from getting worse and save you money in the long run.

When to Call a Professional

Although minor issues can be resolved by hand, there are situations where it’s best to consult a licensed professional, as they are better placed to deal with it properly. Here are some instances when it’s best to call a professional plumber:

  • The tank is damaged beyond repair due to corrosion, rust, age, or cracks.
  • The leak is caused by faulty or damaged components.
  • You are unsure how to proceed with any repairs or maintenance on your water heater.
  • You notice a leak in your hot water system, especially if it is coming from the tank itself.
  • The water heater makes unusual noises, such as popping or hissing sounds.

Hiring an expert for assistance ensures the problem is diagnosed and fixed correctly. Licensed plumbers have the knowledge and experience to identify and repair complex water heater issues.

In my experience, people are hesitant to pay for after sales services, like regular maintenance. I know it’s another cost to worry about, but honestly, these services can actually save you money in the long run by preventing major problems. Like they always say: ‘Prevention is better than cure’.

Mark Longhurst

Water Leaking from the Bottom of Your Water Heater: Key Takeaways

Having a leaky water heater is a problem that needs to be taken care of, but it doesn’t necessarily mean you have to replace the whole thing. Here are the key things to remember:

  • Leaky water heaters can cause problems including water damage and higher energy bills
  • It can be caused by several things, including sediment build-up, corrosion, a loose drain valve, or a faulty tank
  • You can identify the problem by carefully inspecting the water heater
  • Prevention is better than cure, and you can prevent leaks by doing regular maintenance

As always, I want to end this with a final reminder that If you decide to conduct any maintenance or repairs by hand, always follow safety protocols. Turn off the power and water supply, allow the water to cool down, and wear safety gear to avoid potential accidents: better to be safe than sorry.

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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 | 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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