How To Replace a Corroded Water Heater Fitting

A corroded water heater fitting doesn’t just look ugly; it can lead to leaks and potential water damage in your home. Luckily, you can replace the fitting to extend the life of your water heater and avoid spending money on a lot of repairs. In our article, we’ll tell you how to replace a corroded water heater fitting. Included in this guide is a video featuring This Old House’s plumbing and heating expert, Richard Trethewey, who demonstrates the process of replacing a rusted, ready-to-burst fitting.

Understanding Water Heater Corrosion

Water heater corrosion is a common problem many homeowners face. When a water heater’s metal components, such as fittings and pipes, react with minerals and other elements in the water, it causes a chemical reaction that gradually weakens the metal. This leads to rust, leaks, and the potential failure of the water heater system.

Causes of Water Heater Corrosion

There are several reasons a water heater gets corroded, which include the following:

• Age of the water heater
• Electrolysis due to dissimilar metals in the system
• Hard water with high mineral content
• Lack of regular maintenance

Signs of Corroded Water Heater Fittings

If you spot corroded fittings early on, it can save you from more extensive repairs. Look out for the following signs:

• Decreased water pressure or flow
• Discolored or rusty water coming from hot water taps
• Small leaks or moisture around connections
• Visible rust or discoloration around fittings

Preparing for the Replacement Water Heater Fitting

Before you can start your project, collect your tools and practice the proper safety precautions. This will help you save time and avoid injuries. 

Tools and Materials Needed

To replace a corroded water heater fitting, you’ll need the following:

• Bucket
• Close-quarters tubing cutter
• Coupling
• Emery cloth
• New threaded fitting
• Pipe wrench
• Pliers
• Propane torch
• Short length of copper pipe
• Teflon tape

Safety Precautions

Make sure you’re being safe by following these steps:

1. Turn off the gas or electricity to the water heater
2. Close the cold water shutoff valve at the top of the water heater
3. Open all hot water faucets in the house to relieve pressure
4. Allow the water heater to cool before working on it

Step-by-Step Corroded Water Heater Fitting Replacement Process

To properly replace a corroded water heater fitting, you’ll need attention to detail and basic plumbing skills. When you’re ready, follow the below steps.

Drain the Water Heater

Begin by draining some water from the heater.

1. Place a bucket under the valve near the bottom of the water heater.
2. Open the valve and drain enough water to lower the level below the fitting you’re replacing.
3. Close the valve once sufficient water has been drained.

Remove the Old Fitting

Do the following to remove the corroded fitting:

1. Clean the cold water supply pipe with an emery cloth.
2. Cut the pipe using a close-quarter tubing cutter.
3. Remove the old, corroded fitting from the top of the water heater using a pipe wrench but be sure to remove it carefully so that the old fitting doesn’t break off inside the water heater.

Install the New Fitting

Now it’s time to install the new fitting. Here’s how:

1. Solder a short length of copper pipe onto the new threaded fitting.
2. Wrap Teflon tape around the threads of the new fitting, making sure you completely cover it.
3. Tighten the new fitting into the top of the water heater using pliers

Connect the Supply Line

Perform the following steps to complete the installation:

1. Slide a coupling onto the end of the cold-water supply pipe.
2. Align the coupling with the new threaded fitting.
3. Slide it down to straddle the joint.
4. Solder the coupling in place.

Restoring Water Service To You Water Heater

After you’ve installed the new fitting, you can refill the water heater and check for leaks before you restore the power. 

Refilling the Water Heater

To refill the water heater:

1. Close all the hot water faucets in the house.
2. Open the cold water shutoff valve at the top of the water heater.
3. Allow the tank to fill.

Checking for Leaks

Before finalizing the job:

1. Inspect all connections for any signs of leaks.
2. Tighten any fittings if necessary.
3. Wipe down the area so that it’s completely dry.

Restoring Power

Once you’ve checked that there aren’t any leaks:

1. Turn the gas or electricity back on to the water heater.
2. Wait for the water to heat up.
3. Test hot water at different faucets to make sure they work.

Maintaining Your Water Heater and Preventing Corrosion

You can help prevent corrosion and extend the water heater’s lifespan with the tips below.

Regular Inspections

Make sure you perform the following checks every year: 

• Check the anode rod and replace it if necessary.
• Flush the tank to remove sediment buildup.
• Look for signs of corrosion or leaks on fittings and connections.

Water Quality Management

The quality of your water plays a role in corrosion, especially if you have hard water. Here’s how you can help improve your water quality:

• Consider using a whole-house water filter.
• Install a water softener if you have hard water.
• Maintain proper pH levels in your water supply.

Inspecting a Water Heater for Scale and Sediment

Scale and sediment can build up in a water heater over time. The water heater won’t work as well and that buildup could even lead to damage. Inspect the tank for sediment and scale to stay safe and keep that water heater in tip-top shape.

Follow these steps every year to inspect for scale and sediment:

1. Turn off power: Turn off the water heater and let it cool before you start.
2. Drain a few gallons: Attach a hose to the drain valve and drain a few gallons.
3. Look for signs: Inspect the water coming out for any signs of sediment.

Removing Sediment and Flushing the Tank

If you’ve found sediment in your system, remove it by flushing the tank. Here’s how:

1. Turn off the water supply: Shut off the cold water supply to the tank.
2. Empty the tank: Attach a hose to the drain valve and place the hose’s end to a drainage area. Open the drain valve and allow the tank to empty.
3. Flush with cold water: Now that the drain valve is open, turn on the cold water supply for a few minutes to flush out any remaining sediment.
4. Close the valve: Once the water runs clear, you can close the drain valve and remove the hose.
5. Refill the tank: Open the cold water supply and refill the tank.

Addressing Mineral Buildup on a Water Heater

Mineral buildup can clog pipes and reduce water heater efficiency. You can use specialized chemicals to help mitigate that problem. We recommend you use a descaling solution to break down minerals by following these steps:

1. Choose a descaler: Find a descaling solution that works on your water heater type.
2. Turn off the heater: Make sure the heater is off and the tank is cool.
3. Circulate the solution: Follow the manufacturer’s instructions to circulate the descaler through the tank.
4. Flush the tank: After the descaler has done its job, flush the tank with cold water.