Leaky Mug? Contigo's Senior Engineer Can Explain The Problem And Send You A Replacement

Joe’s auto-sealing Contigo mug wasn’t working properly. Moisture was getting caught between the mug’s layers, causing leaks. When Joe wrote to Contigo, he quickly received an unexpected reply from the mug’s designer. Joe writes:

I’ve been using your Autoseal mug for a few months now, and have some quality concerns regarding the product. I’ve already owned two of them – I had to return the first one, and will now likely have to do the same with the second.

The problem specifically relates to the quality around the mug itself; the double-walled plastic version of your product is prone to leaks. The seal on the top of the mug degrades, letting liquid in between the double-lining of the mug. This is accompanied by a hissing sound, as hot water seeps into the mug. No liquid leaks from the mug itself, but over time, the moisture condenses in the mug lining.

The autoseal lid itself is great – I’ve never had any problems with it, and the idea is ingenious. It’s why I bought this mug.

The quality of the plastic mug itself is another thing entirely. I won’t buy the metal version for quality issues as well – all of the metal mugs I saw on the shelf were shredding the plastic lid. I also question the insulation quality of that mug; it’s a bit on the thin side, with little in terms of vacuum insulation.

In short, I’ll probably return my current mug, and I won’t be buying or recommending the product to anyone until the mug itself improves. The autoseal is great, the mug isn’t. I’ll stick with my Sigg Metro Mug, even though it’s a pain to open in the car.

Two hours later, Joe received a response from Contigo:


I’m the engineer that designed the Autoseal mug that you describe. I’m sorry to hear about your experience. We really do appreciate feedback from customers, especially on new products such as the Autoseal mugs.

The problem with the leaking between the plastic walls of the body is an issue that we have improved in more recent shipments. I’m afraid that you may have an early example of the product, manufactured before we caught this issue. The problem typically occurs during dishwasher cleaning. In early examples of the product, the heat of diswasher testing causes a decrease in the “squeeze” on the small o-rings that seal between the walls. This allows water to enter the space between the walls. We have since improved the design to eliminate this problem.

I’m not sure about the source of the hissing sound but it may be the pressure release through the lid when the button is depressed. This is a normal and beneficial feature of the product and allows the pressure to be dissipated safely before the user can drink from the mug.

The issue that you describe for the metal version where the plastic threads on the lid are shredding is one that we caught early on and the later versions do not have this problem at all.

As you point out, the distance between the inner and outer metal walls of that mug is small. The vacuum space between the walls is as thin as 2 to 3 mm in some locations. This is ok. One of the advantages of vacuum insulation is that its effectiveness does not depend on the thickness of the vacuum space. We have performed thermal studies to prove this out. The result is superior insulation in a slender product.

This may be more information than you were looking for but we are dedicated to customer service and appreciate you taking the time to communicate your feedback.

If possible we would like you to send the defective mug to us so that I can study it first-hand. (address is listed below)

Regardless, I will send you a latest version of the metal Autoseal mug today. I am confident that you will be satisfied.



Steve Pinelli
Senior Mechanical Engineer
Ignite USA

Not only did Steve send Joe a replacement mug, but he proved that engineers are good at dealing with customers.

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