Bunn NHBX Leaking From Bottom: Why It Happens and How to Fix It?

Coffee Geek Lab / Bunn NHBX Leaking From Bottom: Why It Happens and How to Fix It?
Yurii Brown

Certified Barista

September 28, 2021

What can you do if your Bunn NHBX is leaking from the bottom?

In most cases, this malfunction is caused by the damage in the silicone seal that connects the water reservoir with the heating tank of your coffee maker.

The good news is — you can repair it at home!

And this guide will show you two ways to do that, along with some advice in case your problem isn’t solved.

Possible Reasons Why Your Bunn NHBX Leaking From Bottom

There are three possible reasons behind the leakage in your coffee maker, and all of them are pretty common. So let’s see what could be the culprit in the malfunction of your brewer.

#1 Damage of the Silicone Seal

This is the most common reason behind the bottom and side leaks, and it happens to all Bunn coffee makers due to the phenomena called “planned obsolescence.”

Bunn NHBX has a silicone seal between the water reservoir and the stainless steel heating tank. Typically, this seal ensures a waterproof connection and prevents leaks. But during use and continuous exposure to hot water, the silicone gasket starts to tear and melt, and it cannot offer you a tight seal anymore.

Damage due to wear and tear can happen to any coffee maker, but with Bunn NHBX, this is the first place to look for.

#2  Improper Usage

Knowing how a drip coffee maker works might still not save you from improper handling. Bunn NHBX is a brewer that requires an initial setup and regular maintenance, which is thoroughly described in the manual.

Failing to follow that, you might increase the chances of leaks and breaks or even ruin your coffee machine altogether.

So make sure to give your brewer the care it needs and reduce the chances of malfunction.

#3  You Haven’t Descaled Your Coffee Maker in a While

The final reason why your Bunn NHBX is leaking from the bottom might be the water. If you live in regions with hard water, you might notice that it forms chalk-like sediment on heating parts of your teapot, kitchenware, and your coffee machine. 

Aside from giving your coffee a weird taste, mineral deposit buildup lowers heat conductivity, making your brewer less efficient. Also, it can prevent the water from properly flowing through your coffee machine, so it will start leaking from the bottom and sides instead.

How Can You Repair Your Bunn NHBX Leaking From Bottom?

How, when you’ve learned about possible reasons behind leaks of your Bunn NHBX, let’s see how you can address them.

Since the most common reason for leaks is the damage to the silicone seal, you can reinforce it if the damage isn’t that bad or completely replace the gasket with a new one.

Let’s go through each method step-by-step.

#1 Reinforce Your Current Silicone Seal

If the silicone seal has a slight tear, you can fix it without replacement and stop your Bunn NHBX leak from the bottom.

You will need the following:

The repair process is straightforward:

  • Using a magnetic screwdriver, open the top of your brewer and remove the plunger. You can then clean the details by rinsing them with water.
  • Now, you should be able to see the silicone gasket. Inspect it for tears and cracks.
  • Take your adhesive silicone sealant and apply it to the gasket evenly in a circular motion, covering all the cracks.
  • Flatten the layer of sealant if needed. You don’t want any bumps on its surface; otherwise, your plunger won’t fit in perfectly, and the brewer will continue to leak.
  • Allow the sealant to dry for a few minutes. Then, assemble your coffee maker and run a test brew to see if it still leaks.

It’s important to use water-based silicone adhesives because they are safe (1) for repairing different devices that come in contact with food and won’t alter the taste of your coffee.

#2 Replace Torn Silicone Seal With a New One

If reinforcing the silicone gasket didn’t help, or if it’s too damaged for that, you might want to replace it with a new filter. You will need:

After you gathered all the supplies, here’s how to repair your coffee maker:

  • Unscrew the top part of your coffee maker using the magnetic screwdriver. 
  • Remove the plastic cover and carefully remove the plunger. After that, you should be able to see the silicone seal.
  • Check the plunger and rinse it under the water if it’s dirty.
  • Now, you need to replace the damaged silicone gasket with a new one. Carefully remove the old and brittle seal. If it’s melted, you can use a sharp tool to separate it from other parts of your coffee maker. 
  • Once the seal has been removed, carefully install a new gasket in its place. Make sure that the new seal is tightly secured and proceed to the next step.
  • Take your silicone adhesive and apply a thin and even layer to a new gasket, so it will stay secured in place and create a waterproof seal. Flatten any bumps and let the adhesive dry for a few minutes.
  • Insert the plunger back into the brewer and mount the top. Then, run a test brewing cycle to see if the coffee maker works without leaks.

If you don’t see any water running from the bottom, congratulations!

You’ve done everything right and can proceed to enjoy your coffee.

#3 Other Options

If you replaced the silicone seal, but your Bunn coffee maker is still leaking, you have two options:

First, you can locate the nearest authorized repair service and bring your coffee maker there to conduct a more detailed search and find the possible reason behind leaks. The company then can repair your coffee maker or offer you a refund if you’re eligible.

Or, in case your coffee maker leaks because of improper handling or damage, you can switch to another type of brewer. Today, numerous coffee brewing methods can offer you more precise customization and help create a perfect cup of coffee, like this selection of the best automatic pour-over coffee makers. Or, you can switch to a totally manual brewing method, such as the French press.


The main reason behind Bunn NHBX leaking from the bottom and sides is the damage and wear of the silicone gasket. The good news is you can repair it at home, either by reinforcing a current seal or by replacing the gasket with a new one.

All you need is a bit of your time, a screwdriver, an adhesive, and a new gasket. Then, follow our instructions and you can enjoy your coffee in no time!

Have you ever repaired your coffee maker from leaking? How did it go? Share your answers below!


  1. Environmental Working Group. Caulks, Sealants & Adhesives. Retrieved from https://www.ewg.org/healthyhomeguide/caulk-sealants-adhesives/ 

Yurii Brown

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