Water Heater Installation: Code Requirements and Guidelines

When homeowners install a water heater, they may be unaware of the code requirements they need to follow. This can be incredibly stressful for homeowners, but it’s a necessary part of the process, and following the proper code requirements will help prevent a costly mistake.

Water heater installation code requirements are in place for fire and other safety reasons. These codes cover the need for a catch pan, prohibited installation locations, required TPR valves and drainage pipes, and more, which we’ll cover in this guide.

It’s easy to feel overwhelmed when dealing with water heater installation code requirements for the first time. That’s why we created this helpful resource guide! Read on to learn all about the installation code requirements for water heaters.

Table of Contents

What Are Water Heater Installation Code Requirements?

Water heater installation code requirements cover the proper way water heaters should be installed and the correct materials that need to be used. These code requirements are in place for the safety of your home and your family.

Water heaters often have tanks full of pressurized water. These tanks have been known to explode when not correctly installed or under extreme temperature fluctuations. They can also leak over time, which can cause severe water damage to your home, especially if the leak happens in a finished area.

The International Residential Code

The International Residential Code (IRC) was created to be a complete and comprehensive code guide for constructing single-family homes, two-family homes (duplexes), and buildings consisting of three or more townhouse units.

The IRC covers everything from the basic frame of the buildings to water heater installations. There are many chapters in the IRC, but chapter 28 is where you want to focus your attention in this instance.

Chapter 28- Water Heaters

Chapter 28 of the IRC covers everything you need to know concerning the proper codes for a water heater installation. An important note to remember is that chapter 28 of the IRC doesn’t necessarily cover everything you need to know to comply with federal and local codes when installing a water heater.

Along with being in compliance with the codes laid out in the IRC, homeowners should check with their state and local guidelines for additional code requirements. Certain states have different codes based on temperature or environmental factors.

Water Heater Installation Code Requirements

While it is important to check for state and local guidelines concerning water heater installation code requirements, starting with those laid out in chapter 28 of the IRC is helpful. We’re going to cover the IRC’s code requirements in detail.

A Pan Needs To Be Installed If There Is Water Damage Risk

Water heaters are prone to leaking when exposed to temperature fluctuations, overuse, or wear and tear. The IRC requires a water catch pan to be installed underneath water heaters when there’s a risk of water damage.

Water heaters installed in unfinished basements, crawl spaces, garages, or outside the home aren’t subject to this regulation. You need a water catch pan when you plan to install a water heater in an attic, finished basement, or another finished area in your home.

The purpose of this is to catch water as it leaks to prevent damage to the home. Leaking water can cause damage to finished floors, ceilings, subfloors, walls, etc. Using a catch pan prevents costly repair bills for homeowners down the road.

Catch Pan Should Be Made Of Approved Material

Water heater tanks get extremely hot, so the water catch pan needs to be made of the right material. This helps prevent the pan from melting or warping due to the heat, which can be a severe fire hazard or lead to water damage due to the pan being faulty.

Water catch pans should be made of number 24 galvanized steel, plastic that’s at least 0.9 mm thick, or another material approved by the manufacturer. Catch pans made of plastic need to meet additional requirements for fire safety reasons. They need to have a flame spread index of 25 or less and a smoke developed index of 450 or less.

Prohibited Install Locations of Water Heaters

Certain areas of your home aren’t suitable for a water heater. These units can’t be installed in closets being used for storage. They also can’t be installed in bedrooms or bathrooms unless there’s a sealed enclosure specifically for the purpose of installing a water heater.

Water Heaters Need To Be Protected From Damage

You must ensure your water heater is protected from damage where it’s installed. The biggest concern here is water heaters installed outside or in garages. You need to minimize the risk of the water heater getting hit by a car or tree by creating and installing a barrier.

Water Heaters With Ignition Sources Should Be Raised

Gas or oil-fired water heaters with an ignition source (either an open flame or a spark) need to be installed on a platform that’s at least 18 inches off the ground unless it’s specified by the manufacturer to be flammable vapor ignition resistant.

This is another fire safety code. Water heaters with an ignition source can emit flammable vapor accidentally, and that vapor often sits near the floor. If the water heater isn’t on a raised platform, then the ignition source could set the vapor on fire, which could potentially burn down the entire house.

Water Heaters Should Be Protected From Earthquakes

This code only refers to homes located in areas where earthquakes pose a serious threat. You’ll need to check your state and local guidelines to confirm whether this rule applies to your home.

Homes in seismic categories D0, D1, D2, and townhomes in seismic category C must follow this code. You’ll need to strap the bottom ⅓ and top ⅓ of your water heater down to protect it from the force of an earthquake.

TPR Valve Is Required

A temperature pressure relief (TPR) valve is a safety requirement for water heaters because its purpose is to prevent an explosion. The TPR will release steam and water when the temperature or pressure becomes too high in the water tank.

Some TPR valves control the release of both steam and water. Other systems use a separate valve for each.

Discharge Pipe Should Be Installed Onto TPR Valve

It’s essential to have a discharge pipe installed onto the TPR valve. The purpose of the discharge pipe is to reroute the hot water or steam coming out of the TPR valve. The discharge pipe sends the water or steam to a safe discharge location.

This code is another safety requirement. Without a discharge pipe, anyone in the room could be burned or otherwise injured when the TPR valve releases steam and hot water.

Discharge Pipe Should Terminate To Pan, Outside, or Floor Drain

There are a handful of requirements about how and where the discharge pipe should terminate the water and steam. The discharge pipe needs to be sloped so gravity can help the water and steam drain.

The discharge pipe should terminate to a catch pan, floor drain, or outside. If your discharge pipe terminates outdoors, then the pipe should be visible to you. Drainage pipes that terminate inside should be a maximum of six inches above the floor.

In addition to these regulations, drainage pipes also should not be directly connected to a drainage system, have a threaded end, have a P-trap, or serve another system. The drainage pipe also should have an air gap and should not be smaller than the TPR valve.

Shutoff Or Check Valves Are Prohibited

You must not install a shutoff or check valve between your drainage pipe and the TPR valve. Doing so can prevent your drainage valve from working properly and cause a backup into the TPR valve. These can create serious safety problems, which is why shutoff and check valves are prohibited.

How To Install A Water Heater To Code

Now that you know some of the basic code requirements for installing a water heater, let’s move on to how to install it so it meets these codes.

1. Set Your Heater In Place

The first thing you need to do is set your heater in place. Make sure it’s at least 18 inches off the ground and a catch pan is set underneath the heater. Catch pans aren’t required in certain areas like outside, in a garage, or in an unfinished area of the home, but they’re still a good idea for preventing potential water damage issues.

2. Install Your T&P Valve

Some water heaters come with the T&P valve preinstalled. If this isn’t the case, then it’s likely in the box. If not, you’ll need to purchase one. T&P valves are very easy to install because all you need to do is twist them into place on the side of the water heater tank where indicated.

3. Install A Discharge Pipe

For this step, you’ll need a discharge pipe made of copper or CPVC. Position the pipe from the TPR valve toward a drain or the floor. If you don’t have a drain nearby, then you’ll want to position a bucket or catch pan underneath the discharge pipe to catch the water. Measure and cut the pipe, so it’s no more than six inches above the catch pan or bucket.

4. Hook Up The Water

You can use a flexible hose kit to hook up the water for this step. You’ll want to apply plumbers’ tape to the threads of the heat trap nipples and then attach the hoses.

5. Install The Fittings

This step may or may not apply to your situation. Some local ordinances require the use of dielectric fittings to join pipes made of a different metal to prevent accelerated corrosion on water heaters. You’ll want to check your local guidelines to see if this applies to you and receive specific instructions.

6. Secure The Fittings

You’ll want to pull out your trusty plumber’s tape again for this step. Wrap the plumber’s tape around the connector body threads. Secure the fittings to the hose and then hold the use up to the pipe while ensuring there’s a little slack. Next, mark and cut the piper, then remove any burrs.

7. Secure The Compression Nut

Next, you want to slide the compression nut and ring onto the pipe. Then, push the pipe into the fitting and tightly secure the nut.

8. Install Seismic Straps

This is another step that may not apply to everyone. If you’re unsure of whether you’re required to use seismic straps in your area, check with local and state guidelines.

For those required to use seismic straps, you need to install one six inches from the top of the heater and eighteen inches from the bottom. Your straps need to be installed into the studs of your walls, so locate the studs first and drill pilot holes.

Next, secure one end of the strap with a socket and ratchet, then wrap it around the heater and adjust the size before securing the strap to the bracket on that side. Do the same process for the other strap.

9. Fill The Tank

Now it’s time to fill up your water tank. Go to the nearest faucet and remove the aerator. Open the hot side and slowly turn on the water supply. Check your water heater for leaks, and fill up your tank if there are no leaks.

If you notice some leaks, immediately turn the water off and tighten your connections before trying again. Keep repeating this process until you’re free of leaks and able to fill the tank.

10. Flush The Tank

Once the water begins flowing out of your faucet, you know the water tank is full. At this phase, you want to let the water flow through the faucet for about three minutes. This helps empty the tank of air and debris.

11. Connect The Wiring

Now you’ll need to get into some electrical work. First, remove the junction box cover from your water heater. Then, attach the ground wire to the green ground screw. Next, twist the wires together with wire connectors.

12. Turn On The Power

Replace the junction box cover on your water heater and flip the circuit breaker switch for your water heater. Your water heater should have power now, but if it doesn’t, turn the circuit back off and check your connections.

13. Set The Temperature Of Your Water

The manufacturer’s instructions should be able to guide you on how to set the temperature of your water. You’ll want to set the temperature to 120 degrees Fahrenheit and be prepared for your water not to reach this temperature for several hours.

14. Check Your Discharge Pipe

You want to wait a few hours after setting the temperature of your water and then check the discharge pipe. If water is already leaking from the pipe, then it means the water pressure inside your tank is too high. If this is the case, turn the pressure down to below 80PSI.

15. Check Aeration

You’ll want to check your faucet after a successful installation to see if water is still flowing freely. If not, then you should remove the aerator from the faucet and allow the water to run freely for another three minutes. This will remove any leftover debris or air from the water tank.

Skills Needed To Install A Water Heater

There are a lot of serious considerations when installing a water heater. Many of the code requirements are in place for fire and other safety reasons, so it’s important to have a strong grasp of several skills when undertaking this task.

To install a water heater, you should be skilled in carpentry, electrical work, and plumbing. If you don’t have experience in these areas, then it’s best to call a professional. They can ensure your water heater is installed correctly and safely.

Common Mistakes When Installing A Water Heater

If you decide not to contact a professional and attempt to install the water heater yourself, then you need to follow detailed instructions and be very careful. Here are some common mistakes people make when installing a water heater that you’ll want to avoid.

1. Buying The Wrong Heater Size

Choosing the right size for your water heater is essential. Water heaters range in size from 30 to 80 gallons, and the proper size for you will depend on the size of your home and how many people are living with you.

Make sure you choose the proper size for your situation because a heater that’s too small will frequently leave you without hot water, and a heater too large will become a massive waste of money on your monthly energy bills.

2. Installing Water Heaters In Restricted Locations

You should always review the IRC code as well as local codes before installation to ensure you’re not installing the water heater in a restricted location.

Bedrooms, bathrooms, and storage closets are considered unsafe locations for water heaters. You’ll also need to take into account the need for a barrier if you decide to install it in your garage or outside, where cars have the potential to damage your heater.

3. Installing A Water Heater Without A Permit

Just because you decide to install your water heater yourself doesn’t mean you’re exempt from getting a permit and ensuring it’s up to code. This is one of the many reasons why experts recommend homeowners recruit a professional to install their water heaters.

4. Having No Drain Pan Below The Heater Tank

A drain pan or water catch pan is an absolute requirement for water heaters. The only exceptions are in unfinished spaces (garages, basements, or crawlspaces) or outside. However, you can benefit from a drain pan even in these areas. This will help prevent water damage, and your water heater won’t be considered legal without one.

5. Water Heater Gas & Shut Offs Not In Sight

Your water heater gas and shutoffs must be in sight. You need to be able to easily access these things in the event of a fire or other emergency. Always make sure the gas and shutoffs for your water heater are in sight and easily accessible.

6. Discharge Tube & TPR Valve Errors

The discharge tube has to be made of copper or CPVC. No other materials are acceptable for this tube. The TPR and discharge tube must be properly installed, and the TPR valve must follow all relevant codes, which we outlined above.

7. Poor Soldering Practices

If you don’t have soldering experience, it’s easy to make a crucial mistake. Poor soldering practices can lead to severe issues with your water heater and can lead to a costly repair bill. Make sure to contact a professional if you aren’t properly trained in this area.

How Much Space Do You Need Around A Water Heater

Water heaters need a decent amount of space around them. This is because water heaters need a certain amount of airflow to allow for proper combustion and ventilation. Your water heater needs clearance around all sides for it to function properly.

Make sure to give your water heater 12 inches of space around all sides. This will ensure it has plenty of airflow for combustion and ventilation.

What Do The Letters On A Water Heater Mean?

Every water heater comes with an “ABC” knob, which helps determine the temperature of the water. If you’re unfamiliar with water heaters, then you probably weren’t sure what these letters meant when you first installed yours.

It’s actually a pretty simple system. The “hot” setting of the knob sets the temperature to 120 degrees Fahrenheit, which is the setting most manufacturers recommend. The letter A stands for 130 degrees Fahrenheit. The letter B stands for 140 degrees Fahrenheit, and C stands for 150 degrees Fahrenheit.

Not every water heater comes with letters. Some models just list the temperatures numerically, and some have codes. So you’ll want to check your owner’s manual if you have any confusion about this.


Water heaters have many necessary installation codes that homeowners are required to meet. Most codes are covered in chapter 28 of the IRC, but some areas also have specific local and state guidelines. This resource provides a basic overview of water heater installation codes and how to install yours properly. However, if you don’t have the necessary skills to do this installation yourself, you should contact a professional to ensure it’s done correctly and safely.