Plumbing, Water Heaters

Water Heater Drain Pan: Why Drip Pans Are Required

drain pan

Water heater drain pans are essential safety components designed to protect homes from potential water damage due to leaks from water heaters.

The plumbing codes change every few years. One of the recent changes is that drain pans under water heaters are necessary when installing inside. If it’s time to replace your water heater (or do drain service on the existing water heater), install a drain pan under it.

In most areas, whether you need a drain pan under a water heater is mainly determined by the location where the water heater is installed. If your water heater is installed in an attic or interior living space, a drain pan is required under your water heater. Drain pans are not required for water heaters inside garages in most states.

Additionally, the drain pan needs a drain pipe that drains to the outside or a nearby floor drain.

Several key reasons underscore the necessity of drain pans:

  1. Prevention of Water Damage: Water heaters hold a significant amount of water. In the event of a leak, the water can cause substantial damage to a home’s floors, walls, and even its structural integrity. A drain pan collects this water and directs it to a drain, preventing it from spreading and causing damage.
  2. Building and Plumbing Codes: In many areas, local building or plumbing codes mandate the installation of a drain pan under water heaters. These regulations are put in place to ensure the safety and protection of properties. For instance, the International Plumbing Code (IPC) specifies the requirements for constructing and installing these pans, including materials, size, and the necessity of an indirect waste pipe for drainage.
  3. Protection in Various Installation Locations: Water heaters can be installed in various parts of a home, including attics, basements, or even within living areas. The location can significantly impact the potential damage a leak could cause. For example, a water heater in an attic without a drain pan could lead to water damage through ceilings and walls, promoting mold growth and structural issues. A drain pan is particularly crucial in these scenarios to mitigate such risks.
  4. Material and Installation Specifications: Drain pans are made from durable materials such as galvanized steel, aluminum, or plastic. They must meet specific thickness requirements to ensure they can effectively contain leaks. They are designed to be wider than the water heater and include a drain fitting to facilitate the safe discharge of water. The pan must also be of sufficient depth to handle the water volume in case of a leak.
  5. Ease of Installation and Maintenance: Installing a water heater drain pan is a straightforward process that can offer peace of mind by significantly reducing the risk of water damage. It is a preventive measure that is relatively simple compared to the potential cost and inconvenience of dealing with water damage after a leak occurs.

When Do You Need a Water Heater Pan?

If you’re unsure whether you need a drain pan under your water heater, this article will help you figure it out. We’ll also talk about the type of water heater pan you should buy and how to ensure your water heater pan has been installed correctly. 

When the International Plumbing Code Requires Drain Pans

504.7 Required pan – Where a storage tank-type water heater or a hot water storage tank is installed in a location where water leakage from the tank will cause damage, the tank shall be installed in a galvanized steel pan having a material thickness of not less than 0.0236 inch (0.6010 mm) (No. 24 gage), or other pans approved for such use.

504.7.1 Pan size and drain – the pan shall be not less than 11/2 inches (38 mm) in-depth and shall be of sufficient size and shape to receive all dripping or condensate from the tank or water heater. The pan shall be drained by an indirect waste pipe having a diameter of not less than 3/4 inch (19 mm). Piping for safety pan drains shall be of those materials listed in Table 605.4.

504.7.2 Pan drain termination. – The pan drain shall extend full size and terminate over a suitably located indirect waste receptor or floor drain or extend to the exterior of the building and terminate not less than 6 inches (152 mm) and not more than 24 inches (610 mm) above the adjacent ground surface. Where a pan drain was not previously installed, a pan drain shall not be required for a replacement water heater installation.

Here are a few of the more common scenarios in which you might be required to use a water heater pan:

  • Anytime your water heater is located above the ground level
  • Anytime your water heater is located in an attic or ceiling location
  • When your water heater is located in an interior living space

In the upcoming sections, we’ll discuss why drain pans for the water heater are required in these situations, but know that you might not have a choice if your locality’s building code mentions water heater pans. 

When a Water Heater is Above the Ground Floor or Inside an Attic

Installation of a drain pan becomes especially important if your water heater is above your home’s ground floor. If a leak happens and you don’t have a drain pan, you could be looking at costly structural damage.

Leaking water in a multi-level home will drip through your walls and ceiling, which can cause an outbreak of mold or even harm the structural integrity of your house. 

If you do sustain a significant leak from a water heater on the upper level of your house, you’ll need to ensure the water damage isn’t affecting any of the load-bearing walls in your home.

Failure to do this could damage these walls, resulting in your house’s partial or total collapse. As such, I highly recommend placing your water heater in the basement, as leaks won’t risk significant structural damage. 

When a Water Heater is Inside a Living Area

While most water heaters are tucked away in a basement corner, some families don’t have the luxury of an out-of-the-way water heater. 

If your water heater is located in an area you and your family use for activities, installing a water heater pan is a pretty inexpensive way to ensure a leak doesn’t damage your belongings or make the room unusable.

This is especially true if the room contains expensive electronics or live electrical outlets, as even small water heater leaks can destroy your equipment or create a fire hazard. 

Best Water Heater Drain Pan to Buy

When choosing a water heater pan, you must consider two distinct characteristics: material and size. 

Water heater pans are often made of aluminum, steel, or plastic. 

If you want something durable, stick to a steel or aluminum pan.

Plastic Water Heater Pans

Plastic pans typically have shoddier manufacturing than metal alternatives, and frequent temperature changes or misuse can cause them to crack and become unusable. A popular rated plastic pan is the Oatey 34063 24 in. Plastic 1 to 1.5 in. PVC Adapter Hot Water Heater Pan is available at

Steel Water Heater Pan

Steel pans are the most durable type, but they are also on the pricier side. The Camco 20932 Water Heater Drain Pan is a popular steel water heater pan available at

Aluminum Water Heater Pan

Aluminum pans are almost as durable as steel pans, so reducing costs makes an aluminum pan the right choice for most people. A highly rated aluminum pan is the Oatey 34079 Aluminum Pan, available at

Choosing the Right Pan Size

Finding the right size of a water heater drain pan can be a daunting process. To figure out the optimal size for your water heater pan, you can follow this step-by-step process:

  1. Get some measuring tape. 
  1. Figure out how wide the water heater is. You can do this by placing the tape measure at one of the heater’s top edges and measuring the distance to the opposite edge. 
  1. Once the width is measured, you can look for a water heater pan. Ensure the pan is at least two inches wider than your water heater. So, if your heater is 30 inches wide, you’ll need a pan at least 32 inches wide. 

After you’ve figured out how wide of a pan you need, you need to decide on a depth. While you might initially think a deeper pan is automatically better, this isn’t always the case. 

Drain pans are only meant to prevent water damage caused by slow, steady leaks. A leaking water heater can fill a shallow pan and can’t drain it fast enough; you’ll probably end up dealing with water damage no matter how deep your pan is. 

The pipes that drain pans direct water can only handle so much liquid at once. A deeper pan will only delay the inevitable if your heater springs a leak too large for your pan to deal with. 

How to Install a Drain Pan Under an Existing Water Heater

Once you buy a water heater drain pan, install it correctly. This task is typically left to a professional, but it’s possible to do it yourself to save money. 

If you’d like to go the DIY route, you can use this step-by-step guide to installing your drain pan: 

  1. Shut off the water lines leading to and from your water heater. If you’d like to be thorough, you can also disconnect them. 
  1. Disconnect the service lines attached to your heater. 
  1. Turn off the main power supply if you have an electric water heater.
  1. Drain the tank of water by opening the T&P valve. It would be best if you didn’t attempt to move the tank before draining the water, as the increased weight will make lifting dangerous. 
  1. Find a second person who can help you lift the water heater. 
  1. Lift the heater and place the drain pan under it. Make sure to point the discharge hole in the direction your drainage pipes will be in. 
  1. Place the heater inside the drain pan and reattach the water lines. 
  1. Close the T&P valve and the drain valve. 
  1. Place a paper towel over all your connections to see if anything leaks. 
  1. Reconnect the supply lines. If you have an electric heater, turn the main power back on. If you have a gas heater, relight the burner. 
  1. Attach the drainage pipe to the drain pan discharge hole. This pipe will remove water from the pan so it doesn’t accumulate and overflow. 

If you need information on replacing the drain valve on your water heater, see our article Replace a Water Heater Drain Valve: DIY Illustrated Guide.

Frequently Asked Questions

Do hot water heater pans work?

When installed correctly, water heater pans are effective at collecting water from a slow leak from a water heater to prevent water damage. Water heater pans can’t stop severe water heater failure. A pan that does not have a drain line, can’t expel the water if it collects. A drain pan must have a drain fitting with a drain pipe that goes outside or a nearby floor drain.

What do you do if water is in the pan under the water heater?

The first step is to check for leaks around the water heater. Leaks can come from the top or bottom, so check the water piping at the top, the TPR valve, the drain connector, and lastly, signs that the tank is leaking. Tighten loose fittings if necessary. Call a professional plumber if the tank leaks or you can’t find the leak source.


Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.