Water Heater Expansion Tank Codes (By State!)8 min read

I talk about water heaters a lot, but for a really good reason. They’re super important, after all, and they provide hot water on demand. But I also talk about them a lot because they do have the potential to be dangerous. They are essentially large tanks of water in your home that can overheat, and they come with some hazards.

Water heater expansion tanks help protect your home from water damage by serving as an overflow for water as it expands. These tanks are governed by national, and state law. The exact codes for your state will vary based on water heater size, type, weather in your state, and expansion tank type. 

If you’re looking for specific water tank expansion codes governing your particular state, I can point you in the right direction. Let’s look at water heater expansion codes state by state and some information about the installation and maintenance of these tanks. 

I take information accuracy seriously therefore everything you’re about to read has been expert reviewed by Mark Longhurst, a professional plumber with over 15 years experience.

Water Heater Expansion Tank Codes By State

Allow me to get technical for a minute: in the United States, plumbing installations are governed by various codes. The overall code, which most states follow, is known as the IPC (International Plumbing Code).

However, to make things slightly more complicated, there are separate codes that exist on the national and state level, too.

The reason for this is that the weather, of course, varies dramatically across the US. States like California, that are prone to earthquakes, need extra protection for water heaters in the form of seismic straps. But if you live in Michigan, you’ll have a whole different set of water issues to deal with.

Plus, if we get down to the city level, there are extra considerations. I’ve lived in a few densely populated cities in my time, and water pressure problems are common when you have that many people packed into a small area. So there may be city-level guidelines to think of, too.

But before we go into it, you should know that if you live in a state without its own water heater expansion tank code, it will be governed by the IPC (International Plumbing Code). If your state does have guidelines, these supersede the national code.

I know I always say it, but I’ll say it once more: always double-check your local plumbing code before beginning any project that involves your water heater or expansion tank.

StateCode Summary
AlabamaAlabama has its own water heater expansion tank code which can be viewed here.
Alaska Alaska, even though it is quite remote, has its own water heater expansion tank which you should review before installing an expansion tank. You can find it here.
ArizonaArizona building code only requires expansion tanks if the water heater is part of a closed system. Those in the area of Phoenix may have additional requirements as the city of Phoenix has its own residential code.
ArkansasArkansas building code has specifications for both gas and electrically-powered water heaters with expansion tanks. You’ll want to double-check the code before installing or removing a water heater expansion tank.
CaliforniaIn California, an expansion tank must be installed if your water heater is equipped with a pressure regulator. The reason for this is that a pressure regulator can cause expanding water not to be able to expand into the city’s main line. 
Additionally, Section 608.3 requires that water heaters with any sort of check valve or backflow protector must also use an expansion tank. If you live in Los Angeles or San Francisco, you’ll want to check for local city regulations as well.
ColoradoIn Colorado, only certain cities require water heater expansion tanks. You’ll want to check with your city or county code before installing or removing one.
ConnecticutIn Connecticut, a water heater expansion tank must be installed with every hot water system. You can find the specifications of the code here.
DelawareLike Connecticut, water heater expansion tanks are required in Delaware. You can find the full code here.
District of ColumbiaAlthough it isn’t a state, the District of Columbia does have its own code governing water heater expansion tanks which should be researched prior to installing or removing one in your home.
FloridaAccording to the Florida Building Code 1009, all water heaters in the state must be installed with an expansion tank. In buildings where there are multiple units, only one is required if the systems are connected. 
The tanks installed must be properly rated for the temperature of the water expected to pass through the system. The size of the tank chosen must be suitable for the size of the system it is attached to. 
GeorgiaIn the state of Georgia water heater expansion tanks are required in code section 607.3 which states that all water heater systems must have a way of controlling increased thermal pressure. Read more about this code here.
HawaiiWhile Hawaii mostly follows the International plumbing code when it comes to water heater expansion tanks, it’s a good idea to take a quick look and double-check it before making any changes to your expansion tank.
IdahoIdaho, like many states, basically follows the international code. There may be some small changes, however, so it’s a good idea to review the code here before starting a project.
IllinoisIllinois state code does require a water heater expansion tank, but because Illinois has so many large cities, many of the locals have their own requirements when it comes to the size and placement of the expansion tank. So take a look at the state code but then don’t forget to check your city code as well.
IndianaIndiana has its own code when it comes to installing water heater expansion tanks which can be found here.
IowaIowa mostly follows the International Plumbing code when it comes to water heater expansion tanks, but if you want to double check to be sure, their plumbing code is here.
KansasIn Kansas, water heater expansion tanks are almost always required, but like Colorado, the bottom line does vary from city to city so check your local county codes before installing or removing an expansion tank.
LouisianaLouisiana mostly follows the international plumbing code when it comes to water heater expansion tanks, but if you want to double-check the code it can be found here.
MaineMaine follows the international plumbing code when it comes to water heater expansion tanks.
MarylandMaryland follows the international plumbing code for water heater expansion tanks.
MassachusettsIn Massachusetts, all hot water boilers are required to have expansion tanks. You can find the full code here.
MichiganMichigan follows the international plumbing code for water heater expansion tanks.
MinnesotaMinnesota follows the international plumbing code for water heater expansion tanks.
MississippiMississippi requires that certain specifications are made when it comes to choosing the size of your hot water expansion tank. You can find the code here.
MissouriIn Missouri, any hot water boiler is required to have an expansion tank within 10 feet of the tank. You can find the full code here.
MontanaMontana follows the international plumbing code for water heater expansion tanks.
NebraskaNebraska follows the international plumbing code for water heater expansion tanks.
NevadaBecause of its proximity to an earthquake zone, Nevada has its own water heater expansion tank codes which must be adhered to when installing or removing a tank.
New HampshireEven though it is small, New Hampshire has its own codes to govern the installation of water heater expansion tanks that you should look at before installing or changing your water heater.
New JerseyNew Jersey mostly follows the international plumbing code, but it is still a good idea to review their local codes regarding water heater expansion tanks, which you can find here.
New MexicoIn New Mexico, any sort of water heater that has hot water storage must have an expansion tank. Review the full code here.
New York StateIn New York, it is required by code 1009 that every hot water boiler be installed with an expansion tank. In buildings with multiple units, one expansion tank is allowed for all units if they are on the same system. 
Expansion tanks can be either the closed or open type but must be properly rated for the pressure of the system they are attached to. Plus, the expansion tank must be located at least 4 feet above any heating element for the boiler. 
North CarolinaExpansion tanks are required in North Carolina plumbing code for all water heaters with a storage tank. Not only that, but the water expansion tanks must also be insulated against cold temperatures which are common in the state in the winter season.
North DakotaNorth Dakota follows the international plumbing code for water heater expansion tanks.
OhioWhile Ohio mostly follows the international plumbing code, there are some size requirements that must be met in the state. Review the full code here.
OklahomaOklahoma follows the international plumbing code for water heater expansion tanks.
OregonIn Oregon, a water heater expansion tank is required for every hot water system whether or not you have a tank. Find the full rules governing hot water expansion tanks here.
PennsylvaniaIn Pennsylvania, water heater expansion tanks are not required. If you live in a heavily populated city like Philadelphia, however, they may be required in residential buildings. Find the full water coder here.
Rhode IslandFor such a small state, Rhode Island does have its own plumbing code which must be followed when installing water heater expansion tanks which you can find here.
South CarolinaIn South Carolina, a water expansion tank must be installed in every water heater whether or not there is a storage tank. Review the full plumbing code before doing any work on a hot water heater.
South DakotaSouth Dakota follows the international plumbing code for water heater expansion tanks.
TennesseeTennessee is unique in that water heater expansion tanks aren’t required on currently existing buildings. If you are building a new building, however, you must install them when you install the water heater. Find all the information you need about this regulation here.
TexasAccording to section 501 of the Texas Building Code, expansion tanks are not required unless they are required by the IPC. Any water heaters installed in Texas, however, do have more stringent draining requirements. 
In section 501.3 it is mentioned that all water heaters installed in Texas must contain drain valves that meet specifications. These drain valves can typically provide relief similar to that of an expansion tank which is why they aren’t always required. 
UtahIn Utah, water heater expansion tanks are only required on closed systems. You can find more information in the full Utah Plumbing Code.
VermontWhile Vermont mostly follows the IPC plumbing codes, it’s a good idea to check the local regulations here before beginning work in the state.
VirginiaLike many other states, hot water expansion tanks are required in every hot water system in Virginia. Find the full code here.
WashingtonIn Washington State, water heater expansion tanks are required on all closed hot water systems. Find the code here.
West VirginiaWest Virginia has its own code governing water heater expansion tanks which can be found here.
WisconsinWisconsin does require water heater expansion tanks in most cases. Find out if your case qualifies by reviewing the local plumbing code.
WyomingWyoming follows the international plumbing code for water heater expansion tanks.

Do Tankless Water Heaters Need an Expansion Tank?

This is a question I get sometimes. Tankless or “open” system water heaters typically don’t need an expansion tank, while most water heaters with a tank will require them because they are a “closed” system and hold a lot of water in one location. 

Because the regulations governing expansion tanks vary widely from state to state, ensure you perform a Google search before installing or removing an expansion tank in your home. As a general rule of thumb, it is better to have a water expansion tank in case it is needed than not have one at all. 

Understanding Water Heater Expansion Tank Codes

A water heater expansion tank functions as an overflow area for water in your water heater. As water changes temperature, either in freezing or hot conditions, it can expand and contract its size.

This is dangerous because water that expands in your water heater can break your water heater or other parts of the appliance. As a result, most states require water heaters to be installed with expansion tanks.

Remember, these codes are in place to protect you and your home (or your building). Disregarding these codes can lead to leaks or damage in your water heater, as well as flooding in the area of your water heater, which can ruin your home and other possessions. This is why it is essential to always follow building codes.

If you can fully understand the code in your area, it’s also best to check the Implementing Rules and Regulations (IRR) of the code or the latest copy of the code. The IPC comes in an annual revised version, and it has the most up-to-date information.

Mark Longhurst

Sizing Requirements

One of the most important parts of installing a water heater expansion tank is ensuring you have the proper size for the system you are installing it on. As you can imagine, the larger the water heater, the larger an expansion tank you will need!

Not to mention that different types of expansion tanks will require different calculations to decide whether or not it is enough for your water heater. 

These calculations are complicated, so unless you have a math degree, it’s best to leave the choice of a water tank to the professionals or use an online calculator if you need an extra hand.

Installation Requirements

Whenever an expansion tank is required, there will also be regulations governing where it must be installed. As a general rule, most states require the expansion tank to be installed at least 4 feet from the heating element of the water heater. 

In states like Texas, there are additional requirements on what supplies must be used to install these tanks, right down to the type of piping. Before you install a water heater expansion tank you should look up local codes to see what is required in your area. 

Remember to check national, state, county, and even city codes before installing a water heater expansion tank. Some apartment/condo complexes may have even more strict regulations on top of local laws, which may be down to specific water pressure problems in certain buildings.

Maintenance Requirements

Like anything else in your home, water heater expansion tanks degrade in quality over time. I would recommend having your water heater expansion tank checked over about 5 years after installation. 

The average lifespan of a water heater expansion tank is about 5-10 years. This means after the 5-year check, it is a good idea to have your hot water system inspected every year just to make sure it’s all ticking along nicely.

How to Comply with Water Heater Expansion Tank Codes State By State

DIY Compliance

It can be tricky to comply with all the codes that govern hot water expansion tanks. Because some states are extremely picky with how these tanks are installed, as well as the supplies that should be used, the DIY route becomes more complicated.

Even if you wish to install the tank yourself, it is best to hire a local contractor to at least inspect your water heater and let you know what needs to be done to bring it up to code before you begin your DIY installation.

Hiring a Professional

Hiring a professional is the best way to ensure all codes are met in the installation of your water heater expansion tank. It is also useful to use a professional because if for some reason a code is violated, you will not be at fault for any ensuing damages.

Because regulations are so location-specific, you should always hire a plumber from your state and city. You should also check their qualifications to ensure they are properly licensed in your state, too. You can check this on their website, using Yelp reviews, or just checking out recommendations from real clients.

I always recommend hiring professionals for any major plumbing projects, and I’d say water heaters are pretty major! They can help with the planning, construction, and even post-operation programs for your plumbing systems as a whole. And they’ll know the local area codes by heart, which makes things much easier.

Mark Longhurst

Water Heater Expansion Codes State By State: Key Takeaways

Basically, complying with plumbing codes isn’t just to satisfy the official rules set by our state, city, or country, but it serves as a guide on making sure your water heater is running properly. Following the codes means you’re less likely to run into a problem later on.

Here are the key things to remember:

  • The IPC (International Plumbing Code) sets guidelines for water heater expansions
  • However, you might be subject to state or city codes, which supersede the IPC
  • Local codes may vary due to unique weather considerations
  • These codes are for your own safety as well as the safety of others in neighboring buildings
  • A licensed contractor should be able to help you figure it out if you’re struggling with the code
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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 http://www.pipesmart.com.au/ | 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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