Water Heater Drain Pan Code: Check the Right Size for Your Water Heater

A water heater is installed in many houses after needing a warm bath in the cold weather. It is an essential home appliance that offers comfort. However, sometimes this water heater fails to support the water. Hence, homeowners should have the correct water heater drain pan code.

The drain pain is helpful to avoid damages caused by the unit. You need to get the proper plumbing codes to use this pan since it is a requirement. These codes have changed over the years. So make sure to check the drain pan sizes correctly.

Water Heater Drain Pan Code

Do you need a pan under water heater or not? It is entirely dependent on your water heater. Since the water volume on the heater unit could risk damaging the bottom of the tank, the one choice to prevent it is to use a drain pan. Unfortunately, the drain pan codes constantly change.

water heater drain pan code

However, it is now a requirement if you want to install it inside the house. In other cases, you must install the drain pan if the water heater is in the attic. For garages, using a drain pan is not an obligation for most places.

The drain pan below the water heater will prevent damage in the house, that why drain pan is required. However, the drain pan must also be installed with a drain pipe. You can place the pipe near the floor drain.

Hence, here is the International plumbing code that requires a drain pan. Check it out:

  1. 504.7 Required Pan

It is required if the place to put the tank of the water heater or the storage is where damage could happen. The tank of the water heater needs to be installed in a steel pan that has been galvanized. The pan’s thickness is also less than 0.6010 millimeters or 0.0236 inches.

  1. 504.7.1 Pan Size and Drain

In this code, the pan should not be less than 38 millimeters (1.5 inches) in depth to adequately catch drips or leaks from the tank. It’s essential that the pan’s size and shape are sufficient to contain any discharge and that it’s connected to a drainage pipe with a minimum diameter of 19 millimeters, leading to an indirect waste pipe.

Additionally, it’s important to ensure that the pan includes a properly installed relief valve to discharge excess pressure and prevent potential damage safely.

  1. 504.7.2 Pan Drain Termination

This code included that the pan drain needs to be extended to full size. It must also terminate in a location suitable for indirect waste or floor drain.

Water Heater Drain Pan Installation

The drain pan must be placed under the water heater to collect the drip from the tank. Installing it yourself could be pretty complicated if you do not know how. Here are the steps:

  • The first thing to do is to turn off the power supply. If you use a gas water heater, then you can shut off the gas supply. Also, do not forget to switch off the water supply too.
  • The next step is to remove the other attachment. Next, you must detach the pipes on the heater since lifting it could cause difficulty.
  • The third step is to drain the water in the tank. You can use the hose that connects to the floor drain. Open the valve, and the hot water will start flowing through it.
  • After that, you could lift the water heater carefully.
  • Then, place the drain pan under the water heater.
  • Replace the water heater above the drain place.
  • The next step is to locate the PVV. Finally, the PVC fitting is provided to attach pipes and other fittings.
  • Attach the PVC and then strap it.
  • Now you can try to use the heater.


The water heater drain pan code must be correct, depending on the type. In addition, since the code changes over the years, you must clearly understand whether your code sizing is proper. Therefore, check regularly on the information available.

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Heater Technician is a skilled author and water heater expert with years of experience in the field. He has authored several articles and books on various aspects of water heater installation, maintenance, and repair.