Water Heater Drain Pan: Why Drip Pans Are Required

drain pan

The water heater is an essential part of your home. However, the water volume it carries can pose a significant risk of water damage when the bottom of the tank leaks. You can take a few steps to mitigate the risk of water damage, one of which is installing a water heater drain pan. 

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), it’s a good idea to install a drain pan under the water heater. But are water heater drip pans required?

In most cases, whether you need a drain pan under a water heater is mostly determined by the location where it is installed. If your water heater is installed in an attic space or inside the 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.

When Do You Need a Water Heater Pan?

If you’re unsure of whether you need a drain pan under your water heater or not, this article will help you figure it out. We’ll also talk about the type of water heater pan you should buy, as well as 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

We’ll discuss why drain pans for the water heater are required in these situations in the upcoming sections but know that you might not have a choice in the matter 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 located above your home’s ground floor. If a leak happens and you don’t have a drain pan in place, you could be looking at a lot of 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 major leak from a water heater on the upper level of your house, you’ll need to make sure the water damage isn’t affecting any of the load-bearing walls in your home.

Failure to do this could damage these walls, which can result in a partial or total collapse of your house. As such, I highly recommend placing your water heater in the basement, as leaks down there won’t run the risk of major 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 that 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 even create a fire hazard. 

Best Water Heater Drain Pan to Buy

When choosing a water heater pan, you’ll need to consider two distinct characteristics: material and size. 

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

If you’re looking for something durable, you should 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 Amazon.com.

Steel Water Heater Pan

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

Aluminum Water Heater Pan

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

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 you have the width measured, you can start looking for a water heater pan. Make sure 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 that is 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 that 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’re probably going to 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 ever 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, you need to make sure you install it correctly. This is a task typically left to a professional, but it’s certainly possible to do it yourself if you want 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. If you have an electric water heater, you should turn off the main power supply.
  1. Drain the tank of water by opening the T&P valve. You shouldn’t attempt to move the tank before draining the water, as the water’s increased weight will make it dangerous to lift. 
  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 of your connections to see if anything is leaking. 
  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 collects. It’s crucial for a drain pan to have a drain fitting with a drain pipe that goes outside or a nearby floor drain.

What to 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 is leaking or you can’t find the leak source.

If you’ve stopped the leak, use a towel to soak up and remove the water inside the pan. If the drain pan doesn’t have a PVC drain fitting and discharge pipe, call a professional plumber to install one.


Water heater maintenance is an integral part of the longevity of your water heater. Want your water heater to last 20 years or longer? Our article Water Heater Maintenance Tips to 2X Your Tanks Lifespan will help you keep your water heater running for 20 or more years.


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.