Hot Water Heater Leaking From The Bottom

Oh no! Your water heater is leaking. Depending on when you find out your water heater is leaking and the leak’s severity, a pool of water under your water heater can ruin your day in a heartbeat. A leaking water heater means two things. Call a plumber for repairs or start planning for a new water heater. 

Water heaters usually leak from the top, the side, or the bottom. However, bottom leaks may be more severe since they could mean your heater has completely broken down. If you notice a bottom leak, you either have a drain valve problem or a tank problem. 

Leaky water heaters are common. It might be because of incomplete repairs, loose components, or your tank has run its course, and it’s time for a new one. We get to the bottom of it and find out the causes and your next move if your water heater’s leaking. 

What Causes a Hot Water Heater to Leak From the Bottom?

Water leaking from the bottom of a water heater is usually a problem in two areas. You could break it down to a maintenance issue, intentional damage, negligence, or good old aging. These are the two common causes.

Faulty Drain Valves

The drain valve is located near the base of the water heater. What is it about a drain valve that makes a water heater leak from the bottom? During routine maintenance, the plumber might leave the drain valve improperly secured. It could be a loose rubber gasket, or the drain valve is entirely loose. 

Typically, a faulty drain valve is not a big deal. A water heater leak from a drain valve might be minor, probably only leaving you with a drip. It might even take time for you to notice. However, you can’t be comfortable with a drippy faulty heater. That drip will seep into the floor and ruin the ground. 

There are plastic drain valves and brass drain valves. Plastic drain valves might be more susceptible to breaking. It is, therefore advised, that you replace plastic valves with drain valves first. 

Another problem with the drain valve is that it could be worn out. You’ll notice the plumber’s tape near the head of the valve is tattered. The deterioration of this white tape is common in brass drain valves. You can fix these minor problems with a wrench, a fresh wrap of plumbers tape, and elbow grease. 

Corroded Tank Lining

Corrosion might be a bigger problem than you thought if you discover it late. Sediment buildup is the primary cause of corrosion in water heaters. Sediment eats at your tank from inside. It could take a long time to discover the damage, especially if you don’t regularly inspect your water heater. 

What starts as a drippy leak can become an uncontrollable stream at the bottom of the tank if you keep ignoring the problem. 

What Do You Do If Your Water Heater Is Leaking from the Bottom?

At this point, let’s assume the damage from the leak isn’t too severe. You have two options, fix it yourself or call a plumber. Since you need to stop the leak as soon as possible, you can check it out before making that call. 

Check The Source Of The Leak

This far, you know the leak is at the bottom of the tank, but you don’t know if it’s an internal problem or a drain valve problem. Assessing the leak area means checking where the leak’s source. 

Run your finger along with the mouth of the drain valve. If you feel some wetness on the wetness, your problem is likely the valve. Also, check around the valve and look for signs of leakage around the drain valve thread. 

Once you confirm the drain valve as the source of the leak, you can either tighten it or replace the valve entirely. Twist it counter-clockwise with a size-appropriate wrench to remove the faulty valve and replace it with a new one.

If the leak is coming from within the tank, there is substantial corrosion in the tank. Sediment buildup in the tank eats away at the lining in the tank. Over time, the water heater gets thinner and finally cracks. The leak at the bottom starts as a drip before it becomes irreparable.

Stop Further Damage

Shut off the water heater and cut off the water heater’s power supply. Alternatively, you can also shut off the water from the main. Shutting off the electrical power won’t affect other house appliances since most water heaters have a dedicated power supply. 

For gas water heaters, the OFF dial should be on the side of the heater near the bottom. 

Why Home Inspections Are Important x
Why Home Inspections Are Important

How Do You Replace the Drain Valve on a Water Heater?

1. The First Flush

Before changing the drain valve, make sure there is no sediment in the tank. To do this, connect the drain spout to a garden hose that drains the water outside. Make sure the water pressure is on. 

Open the drain valve for about five seconds and close it. Opening and closing the drain valve unsettles any sediment in the tank. Repeat the process a few times until you are sure your tank is clear of all sediments. 

After shutting off the water supply and power supply (in electric models), check the pressure by turning on all the hot water faucets. You’ll know the water is shut off if the initial burst of pressure tapers off to a drip. However, leave one hot water faucet open to alleviate any pressure. This faucet should be the one closest to the water heater. Use the tap in the shower or the tub. 

2. Open the Drain Valve

Opening the drain valve should be easy. You can open it by hand. If it proves difficult, use a flat-head screwdriver to get it loose. It is advisable to use a garden hose to reduce your workload. Otherwise, a bucket should work. However, that comes with repetitively draining the bucket as it fills. 

3. Flush the Heater

Fill the tank with water and open the tank. This step is only to make sure your tank has no sediment after the repair. It might take a few flushes to get a clean run-off. Make sure the tank is empty for the next step. 

4. Remove the Old Drain Valve

Turn the drain valve counter-clockwise to remove it from the tank. A pipe wrench, channel lock plier, or adjustable wrench should work.

5. Install a New Drain Valve

Wrap the new drain valve in plumber’s tape around the threads for a tighter fit. The new drain valve should point in the same direction as the old valve if the fit is tight enough. You can check if it’s properly installed by turning it clockwise. You should feel some resistance. 

 6. Refill the Tank

Close the drain valve and remove the garden hose. Turn the water back on and wait for the open faucet to let off nothing but water. Let the water run for about 5 seconds. There shouldn’t be any sediment in the water. 

Turn off the faucet. Go round the house, briefly turning on all the water heaters. This is to remove any air from the taps. 

7. Turn On the Heater

Turn on the water heater and the power. Give it an hour, then check if the water heater function runs correctly. 

Over the next few days up to a week, keep an eye out on your newly installed drain valve to check if it has any leakage. 

How Much Does It Cost To Replace a Drain Valve

Replacing a drain valve is cost-effective to stop a hot water heater from leaking from the bottom. A plastic drain valve can cost about $10. However, plastic drain valves are not preferable since they are more prone to damage than brass drain valves. 

A brass drain valve can cost from $17 to $30 if it has a garden house cap.

To get the actual cost of a replacement, you have to consider the cost of a plumber, too. Plumbers charge by the hour. The going rate for a plumber is between $40 and $150 per hour. Repairing a leaking water heater can take up to 3 hours. Your repair budget, excluding the cost of material, would be about $150 to $450. 

Replacing a Leaking Water Heater

Replacing the leaking water heater is the last resort if the tank is beyond repair. Hopefully, it will have given you adequate service by the time it springs a leak. A typical water heater will last about 12 years before it is ready for complete replacement. 

Still, 20 years is typical with proper maintenance. 

You have a lot of options when you want new water heaters. Installing a new water heater will cost you between $1100 to $3500, depending on the size of the water heater. 

If you have an issue with tank-type water heaters, try tankless water heaters from reputable companies such as Bradford White, Rheem, A.O. Smith, and State Water Heaters

Should I Turn Off My Hot Water Heater If It Is Leaking?

If you notice your water heater leaking, you need to turn it off immediately. Turning off your hot water heater prevents any water damage, and it helps you investigate the source of the leak without worsening the situation. 

Your water heater and most water heaters, too have a valve at the top of the water heater. The valve is the shut-off point. It is either a pull-down handle or a valve that you should turn clockwise to turn off. 

Sometimes you might notice a leak when the water leaking is too hot to approach the area. Also, the water heater may be in an inaccessible location. In such a case, professionals advise that you shut off the water from the home’s main supply. 

Depending on your knowledge of water heaters, you can investigate the problem or call a professional plumber near you. 

How Long Will a Hot Water Heater Last Once It Starts Leaking?

A leaking water heater might not pose an immediate danger, but it might be time to think of a new one. Depending on the severity of the leak, you may have a few weeks left to use it or a few more years if the issue is fixable. 

A week might be stretching it if the leak from the bottom is not too bad. A leaky tank can fill your basement in 5 days. In the same breath, a 20-gallon an hour leakage from a busted tank means your heater is beyond repair. It cannot keep hot water hot if there’s cold water incoming. 

It is advised that you shut it down as soon as possible. Otherwise, there is the risk of the water heater forming a steam bubble and exploding from pressure. 

Will a Leaking Water Heater Explode?

Yes, a leaking water heater WILL explode if you continue running it. Three reasons can make your leaking water heater explode. 

  • Corroded anode rod
  • Excessive sediment buildup
  • Gas leak

A leaking water heater can have a bad anode rod or excessive sediment buildup that eats away at the tank. With excessive sediment buildup, water and air will concentrate at the bottom of the tank, causing a pressure buildup. You might hear pop noises due to the pressure. If it is left unchecked, the water heater will give way to the pressure and explode. 

The right move to prevent pressure buildup in your water heater starts with the correct installation. The proper installation means you will have a lower likelihood of a gas leak or a pressure buildup that eventually leads to the heater’s explosion

Can I Take a Shower If My Water Heater Is Leaking?

Yes, you can take a shower if your water heater is leaking. The leak would have to be small enough to maintain more hot water than the cold water coming in. However, you should only shower if you have a leaking water heater if you plan on checking the main problem. 

Showering with a leaking water heater is dangerous since it exposes your home to water damage, potential pressure buildup, and explosion in the worst-case scenario. 

Final Thoughts

Life will be tougher without a functioning water heater if you are used to the convenience of having one. Maintaining your current water heater means regularly checking for any signs of aging and breaking down. You can have a professional plumber run complete maintenance checks twice a year. 

Also, you can make it a routine to run heater health checks every couple of weeks to ensure everything is in top shape. 

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Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started to help people better understand the home inspection process and answer questions about homeownership and home maintenance.

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