Repair a Leaking Water Heater: DIY Step by Step Guide


leaking water heater

A water heater that’s leaking never comes at a convenient time. When a water heater starts to leak, the mere thought of a repair can be scary.

A small leak can be a sign that a bigger problem may exist. If left unattended, a small leak can turn into a catastrophic failure which could lead to severe water damage to the living areas inside your house. Major water damage is very expensive and could cause your family to be displaced for an extended period of time.

Can a leaking water heater be repaired? Maybe. A water heater leaking from the top around the cold water inlet or hot water inlet can usually be repaired connections A leak around the temperature & pressure relief valve can usually be repaired.

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What if my water heater is leaking from the bottom? If your water heater is leaking from the bottom, it may be leaking from the drain valve or the internal tank. Drain valves can usually be repaired. However, if the internal tank is leaking, the only repair is to replace the water heater.

Water heater repairs do not have to be scary. Most DIYers can repair their own water heater when a leak occurs. If you’re not the handyman type, most plumbers offer emergency service and can repair a water heater for a few hundred dollars depending on the severity of the repair. 

In order to repair a leaking water heater, we need to first determine what the cause of the leak is. Sometimes this is an obvious step while other times it may require some investigation.

How to Fix a Leaking Water Heater

When diagnosing a leaking water heater most of the time the problem looks worse than it actually is. In this section, we will look at the steps needed to help you find where the problem is located and then what you can do to fix it.

But first, let’s be sure the water heater is really leaking. 

How to Inspect a Leaking Water Heater

Not all visible water around the bottom of the water heater is caused by a leaky water heater. One of the most common causes of water on the floor, tank, or supply lines is condensation.

Condensation forms when water vapor in the air changes from a gas to liquid form. Moist air around the water heater contacts hot and cold surfaces causing water to form on the surface of the water heater or piping. Some of this water may end up on the floor resembling a leak.

Water Heater Condensation

Condensation often occurs on the water heater tank and pipes, particularly in water heaters that are:

  • Older water heaters that are not well insulated. 
  • Water heaters located in an uninsulated area; such as in an exterior storage cabinet, crawl spaces, basements, or attics. 
  • Water heaters that have exterior damage which may have damaged the interior insulation.
  • Water heater thermostat is set to high causing the water heater to heat up beyond recommended temperatures. 

Here are some steps to help determine if the water is from condensation or a leak in the water heater. 

  1. Turn off the electric breaker or service disconnect for the water heater. If your water heater is a gas unit, set the fuel knob to pilot or a vacation mode.
  2. Dry up as much of the water as possible and do a visual inspection of the water heater for oblivious signs of leakage. Allow the water heater to sit for several hours to see if the water returns. 
  3. If the water does not return, restore power to the water heater and set the temperature to a maximum of 125°. Monitor the water heater for a few hours.
  4. If the water returns, consider replacing the water heater if it is over 10 years old or has visible damage to the water heater. 
  5. If the water heater is new and no damage is visible, consider investing in a water heater blanket to insulate the outside of the water heater.  See our article Do Water Heater Blankets Save Money for more details.
  6. It is also recommended that water supply pipes located in uninsulated spaces be insulated to protect again both freezing and condensation. 

Locate the Water Heater Leak

leaking water heater

Once you’ve ruled out condensation as a source of the water on the floor around the water heater, let’s look at some other possible causes.

To do this, let’s look at the next few steps:

Turn off the Power to the Water Heater

it’s important before you begin any work on the water heater that you cut off the power to the water heater. 

For an electric water heater, you’ll need to turn off either the service disconnect located beside the water heater or the circuit breaker located inside the electrical panel box.

For gas water heaters, you’ll need to turn the control valve On the bottom of the tank to the offsetting before beginning any work on the water heater. It is not advised that you turn off the fuel shut valve because these are prone to failure. 

Inspect the Water Heater for Leaks

You’ll need to inspect the water heater thoroughly to locate the source of the leak. In some cases, this may be obvious, while in other cases it may not be.

  1. Inspect the cold water supply line connections for leaks. 
  2. Inspect the hot water supply line connections for leaks. 
  3. Inspect the temperature & pressure relief valve, connection, and the attached discharge pipe. 
  4. For Electric Water Heaters – Remove the top element cover to determine if the leak is coming from the seal around the top heating element. 
  5. For Electric Water Heaters – Remove the bottom element cover to determine if the leak is coming from the seal around the bottom heating element. 
  6. Inspect the drain valve and connection as a source of the leak. 
  7. Inspect the exterior of the water heater tank around the seams for rust or damage. 

Turn Off the Cold Water Supply 

After the power supply has been turned off to the water heater, you’ll need to turn off the water supply to stop the flow of water into the tank. 

The water shut off valve is located on the cold water supply pipe coming into the water heater. 

In some older water heaters, there may not be a shut off valve at the water heater. If this is the case, you’ll need to turn off the water at the meter base or at the well pump.

How to Repair a Leaking Water Heater

In this section, we will look at some of the areas where water could be leaking from your water heater. 

Some repairs are not too difficult if you have some DIY experience with minor plumbing repairs around your house. 

If you decide to repair your leaking water heater yourself, we’ve included a few steps for the most common sources of water heater leaks. 

If the repair appears to be more difficult or you feel uncomfortable with the job you should contact a licensed plumber for assistance. Before we begin, we must caution you

WARNING: The water inside a water heater is very hot and may present a scalding hazard. Some water heater repairs should only be done by professional plumbers. Improper repairs can lead to catastrophic damage due to flooding which can be expensive to repair. If you do not have experience working with plumbing systems you should contact a licensed plumber to repair or replace your water heater. 

Draining the Water Heater

Some repairs will require that you drain the water heater. These steps will direct you on how to do this. You don’t need to drain your water heater quite yet. These steps will be here if you need to drain your water heater to replace a component.

  1. With the water heater power turned off and water supply turned off, connect a garden hose to the drain outlet at the bottom of the water heater.
  2. Direct the hose to a floor drain, nearby sink or to the exterior. 
  3. Open the hot water side at a nearby faucet to allow air to enter the water heater. This helps to release pressure from inside the water heater. 
  4. Open the drain valve to begin draining the water heater.  
  5. Drain the entire water heater tank. 

Cold Water & Hot Water Supply Connections

Inspect the cold water and hot water supply connections typically found on the top of the water heater. 

The water supply pipes will likely be made of copper, CPVC, or Pex. If you find water leaking around the fittings, you may be able to tighten the fittings with a pipe wrench. 

This should be done carefully because overtightening the pipe fittings could crack the fitting compounding the problem. Some fitting, such as Pex) require specific tools to work with Pex pipe 

If you can’t tighten the fittings or if rust is visible on the hot or cold supply pipe connections, you’ll need to contact a licensed plumber. 

Leak at the Temperature & Pressure Relief Valve

The job of the temperature and pressure relief valve (also referred to as a T&P valve) is to relieve overheating and excessive pressure from inside the water heater. In the event, if overheating or excessive pressure is present inside the water heater the T&P valve will open to allow hot water to escape the water heater. This also reduces the pressure inside the tank.

For more details about Temperature & Pressure Relief Valves and why it is leaking see more details in our article Why Your Water Heater Pressure Relief Valve is Leaking.

The T&P valve can leak from two locations:

  1. From the T&P valve itself or
  2. The seal around the T&P valve has failed. 

First, we need to determine if the leak came from the temperature & pressure relief valve due to the proper operation of the valve or failure of the valve. To do this we need to:

  1. Turn the power/gas back ON to the water heater.
    • For electric water heaters turn the breaker or the service disconnect ON.
    • For gas water heaters turn the fuel control back to ON. 
  2. Reduce the temperature on the thermostat. 
    • For electric water heaters, you may need to remove the top element/thermostat cover to access the thermostat control setting.
      • Most have a dial temperature setting. Some thermostats will say Hot to Very Hot others will have temperature readings from 110 to 150 degrees.
      • Some electric water heaters have thermostats on the top and bottom elements. Others may only have a top thermostat. If you are unsure try to Google “Your Water Heater Brand Model # manual” for example “State ES652D0RT manual”. Most manufacturers have their manuals available for download online.
    • For gas water heaters, you can adjust the temperature using the control knob on the front of the water heater. 
      • Much like electric water heaters, some control knobs will list temperatures ranging from Low to 160 degrees. Others will list from Low to Very Hot.

With the temperature turned down if water continues to leak from the T&P valve, your T&P valve is likely the problem. The T&P valve could have sediment trapped in the valve or the T&P valve has failed. To find out, we have a few troubleshooting steps to follow.

  1. Let’s flush the temperature & pressure relief valve. Place a bucket under the T&P valve or T&P discharge pipe to collect water. If your T&P discharge pipe is directed to the exterior no bucket is needed.
  2. Open the valve to flush the T&P valve. Allow the valve to drain for a minute or so to thoroughly flush the valve of sediment. 
  3. Close the T&P valve.
  4. Observe to see if the T&P valve continues to leak. If the T&P valve stops leaking this likely cleared trapped sediment preventing the T&P valve from closing fully.
  5. If the T&P valve continues to leak, the T&P valve is likely faulty and needs to be replaced. 

Replace the Temperature & Pressure Relief Valve

leaky T&P Valve

To do this step you will need to drain the water heater. The following steps will help you to replace the T&P valve

  1. Remove the attached discharge pipe from the T&P Valve.
  2. With a wrench or a set of channel lock pliers, remove the old T&P valve from the water heater. 
  3. Inspect the T&P valve mounting flang to see if the threading is rusted. Using a rag clean the threading on the water heater inlet. If really dirty you may need to use an old toothbrush or a small wire brush if needed to clean the mounting flange. If the mounting flange can’t be cleaned, it’s likely the internal tank is just as bad (or worse) and replacement of the water heater is your best option. If the mounting flange is clean proceed to step 4.
  4. In a clockwise motion, wrap Teflon tape tightly around the threaded end of the new T&P valve. Four or five passes should be sufficient. Be sure all the threads are covered.
  5. Attach the new T&P valve to the water heater firmly. Be sure the valve is pointed down. 
  6. Open the cold water supply to fill the water heater. Do not turn the power on until the tank is completely filled to not damage the water heater. 
  7. Once the water heater is filled and water begins exiting the open hot water tap at the sink, close the hot water tap and turn the power ON to the water. 
  8. Observe to be sure there are no leaks around the T&P valve threading.
  9. Reattach the discharge pipe to the new T&P valve. 
  10. Monitor the new T&P valve a few days to ensure no leaks occur. 

Leak at the Top or Bottom Heating Elements 

If you have an electric water heater, the leak may be present at the top or bottom heating element. Each heating element has a seal that over time becomes worn causing it to leak. While this isn’t very common, it does happen and deserves to be checked. 

To check for a failed heating element seal you will need to do the following:

  1. Locate and remove the access panels on the side of the water heater.
  2. Move the insulation so that you can view the area around the heating elements. 
  3. Inspect for signs of water or rust around the heating elements.
  4. If you see water or rust around the heating element seal, you’ll need to replace the seals. If replacing one of the seals, I recommend replacing both heating element seals.  
  5. Follow the instructions above to drain the water heater. You will need to drain the water heater in order to remove and replace the heating element seals.
  6. With the tank drained, disconnect the wiring and remove the element with a socket or heating element wrench. Before removing the wiring, take out your phone or a camera and snap a picture of the wiring connections so that you can refer back to when installing the heating element. 
  7. Clean the mounting flange that holds the heating element. Remove the old gasket before installing the new one. You can purchase heating element seals in the plumbing department of your local hardware store. I also recommend taking this opportunity to replace the heating elements.
  8. Apply the new seal and reattach the heating element with a socket or heating element wrench. Be sure the heating element is secure but do not over tighten as this could damage the new seal.
  9. Using the picture you took as a guide, reattach the wiring to the heating elements. 
  10. Open the cold water supply to refill the water heater.
  11. Once the water heater is filled, close the hot water tap at the sink.
  12. Turn the power to the water heater ON at the breaker or service disconnect. For gas water heaters, turn the control knob from Pilot/Vacation Mode back to ON.
  13. Monitor the area around the heating elements to be sure the leak has stopped. Once confirmed, reattach the cover panels to protect the heating element and wiring connections.

Get more information and a demonstration on how to test and replace heating elements in our article Test & Replace a Bad Water Heating Element: DIY Guide.

Leak at the Drain Valve 

The drain valve, located at the bottom of the water heater, is used to drain the water heater for service and maintenance. Typically if a drain valve begins to leak it’s usually because there is debris or sediment lodged in the drain valve or the drain valve is faulty. 

To determine the reason the drain valve is leaking you should do the following:

  1. You will need a stocking, a bucket or a garden hose to drain the water heater and collect any debris exiting the drain for analysis. 
    • If using a bucket, attach a stocking around the drain valve. 
    • If using a garden hose, connect one end to the drain valve and the opposite end attach a stocking to the garden hose.
  2. Open the hot water tap at a nearby sink to release pressure inside the water heater.
  3. Open the drain valve to begin draining the water heater. 
  4. After a few minutes, close the drain valve and check the stocking for debris.
    • If you see pieces of plastic in the stocking, the plastic dip tube located inside the water heater has likely broken off inside the water heater. If this is the case there is no repair for the water heater. Replacement is the only option.
    • If the water heater will not drain or is draining very slowly, it’s likely large chunks of sediment have clogged the drain valve. Replacement of the water heater is the only option.
    • It is common to see sediment in the stocking. Continue with a full drain and flush of the water heater until no more sediment is present. 
  5. Close the drain valve and begin to refill the water heater. If the drain valve continues to leak the valve is faulty and needs to be replaced. To replace the drain valve continue to the next section.

Replace the Drain Valve

See our Replace a Water Heater Drain Valve: DIY Illustrated Guide for a step by step guide to replace your drain valve. We include an informative video as well.

  1. Completely drain the water heater.
  2. Using a wrench carefully remove the old drain valve. If the drain valve on your water heater is plastic, be very careful to not break the plastic drain valves off inside the water heater.
  3. After successfully removing the drain valve, clean the mounting flange removing any rust and sediment. 
  4. Purchase a new drain valve from the plumbing department at your local hardware store. Brass valves are the best choice. 
  5. In a clockwise motion, wrap the threaded end of the drain valve four or five times with Teflon tape. Be sure the tape is tight and fully covers the threaded end. 
  6. Using a wrench, screw on the new drain valve and secure firmly. Be sure the valve points downward. 
  7. Open the cold water supply and begin to refill the water heater.
  8. Once the water heater is filled, restore power to the water heater.
    • For electric water heaters, this includes turning the breaker or service disconnect back ON.
    • For gas water heaters this entails moving the control valve from the pilot/vacation setting to the ON setting and adjusting to your desired temperature. 
  9. Observed a new drain valve install to be sure no leaks are present.

Leaking from the Internal Tank 

Lastly, Look for signs around the bottom of your water heater such as rust or staining around the metal seals. This is generally a good indication that the inner tank of the water heater has failed and water has started to seep out of the tank.

If the above attempts have all failed to prevent the water heater from leaking, your only option is to replace the water heater. 

Once the inner tank of the water heater has failed there is no repair for the water heater. Do not attempt to remove the outer shell of the water heater. Internal leaks cannot be repaired and replacement is the only option. 

Unless you are very familiar and have experience working with plumbing and water heater installation it is recommended that you call a licensed plumber.

If at this point or at any other point you are uncomfortable with examining and repairing your water heater you should contact a licensed plumber.

Water heater prices vary based on the size of the water heater, the type of water heater (gas, electric, heat pump, or tankless). Consult with a licensed plumber to help you make the choice that is right for you.

New Water Heater Installation Costs

According to HomeDepot.com, the average cost of a new water heater around $1,308. Nationwide costs typically range from $952 to $2,098. This replacement estimate includes the following components: 

  • Basic tank water heater – typical water heater size is 40 or 50 gallons.
  • Installation materials such as fittings, shut off valves, piping, etc.
  • Installation labor by a licensed and insured plumber.
  • Removal and disposal of the old water heater in accordance with local laws.

If you are planning to buy and install a water heater yourself, you can expect to pay between $350 to $2000 depending on the size and type of water heater you decide to purchase. The average tank-style 50-gallon water heater costs between $600 to $700.

HomeInspectionInsider.com is owned and operated by Hubert Miles is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. HomeInspectionInsider.com also participates in affiliate programs with other affiliate sites. Hubert Miles is compensated for referring traffic and business to these companies.

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 HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.

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