How to Remove the Stench from Sippy Cups

Please tell me I’m not the only one who frequently finds nasty, old sippy cups full of curdled milk!!!

We recently left our favorite Contigo cup at church one Sunday morning. We thought we would pick it up the next time we were there, but we forgot. And then we forgot the next time as well. Finally, two weeks later, we remembered the cup. It was partially filled with milk and was absolutely putrid. It’s a $17 cup (and worth every penny, in my opinion), so I was not about to just throw it away!

We washed it. And washed it. And washed it. No matter how many times we washed it with soap and water, it still stunk. Even being washed on the sanitizing cycle in our dishwasher didn’t do the trick. It’s stainless steel, after all.

And then, like manna from Heaven, I suddenly remembered the magical cleaning powers of white vinegar…

I thought that maybe, just maybe, this might do the trick.

So I filled the cup to the top with white vinegar and also filled the lid. I let it sit overnight.

And guess what???


So…the next time you nearly vomit from the perils of curdled milk in a sippy cup with a stench that must be otherworldly…go grab you some white vinegar!


  1. So glad I’m not the only one who does this(leaving sippys behind)! Also you can use baking soda and let it sit for a while baking soda helps absorb odors! After your cup sits with baking soda for a while then put the vinegar in there (make sure you do this over the sink because it’s the “volcano” reaction) and then wash like normal. I also use this to clean drains. :)

    1. I just found a cup with some milk in it as I was cleaning my daughter’s room. Gross! I’ll have to remember this tip and use it. Oh the powers of vinegar.

  2. Haha, I’ve done this trick before. I eat breakfast at work and often I have cereal. Since I don’t want my cereal soggy by the time I get to work, I take it dry and bring milk in a stainless steel thermos. And even though I wash out my thermos as soon as I use the milk, I sometime get some milk that gets up under the rubber gasket ring that drips into the thermos and then stinks. I’ve used the vinegar trick several times for that. And I also now put a piece of paper towel between the lid and container after I’ve done washing it so that if there is any milk that didn’t get cleaned out of the rubber ring, the paper towel catches it.

  3. Great tip, but what about the smell of vinegar afterwards? Now that I’m pregnant, everything that I used to enjoy cleaning with vinegar disgusts me. I’d really be afraid of the vinegar smell coming from something I drink out of as I have a stainless steel thermos, too.

  4. Great tip! We use those same sippy cups in the picture. :) I have such a hard time getting the top clean. I’ll have to try this one. Just wondering if the vinegar smell goes away though? I can’t imagine drinking milk from a cup that smells like vinegar…

  5. The hide and seek sippy cups…yes, we know them well. It’s almost as if they take delight in taking a few days off. This is a great tip, I’ll try it next time. Thanks!

  6. I usually use baking soda mixed with water and let it sit for a couple of days. Works like a charm but I’m going to try this too! Thanks for sharing!!

  7. I run vinegar through the dishwasher with vinegar in it. Just dump a bunch in and run it with the plastics in it. Gets rid of the everyday funk that can accumulate.

  8. So very glad I found your site! I have two little guys that use the exact same cups in your picture and yes I find them in the weirdest places with curdled milk in them! Thankfully I’m not the only one! :) I’d let them sit over night in very hot water and it never works! Thank you all for the idea especially the little valves they are tricky to clean!

  9. Thank GOD for this article! I wish I had found it 2.5 years ago. I have been throwing the cups out every six months and buying all new because of this! So much money down the drain but I couldn’t stand how the cups smelled even immediately after washing them! I felt like a terrible mother if I was to let him drink out of them even though I knew they stunk… Agh!

  10. I’m a runner, and I’m guessing this will help extend the life of my water bottles, which always end up in the garbage after the smell of sports drinks starts to permeate. Going to give it a try!

  11. That’s a very good idea. All my family uses sippy cups for sports and my kids use them daily, and we change them too often, because of the bad smell that always appears. Your idea seems to work perfectly good and I’m definitely trying it. Thank you for sharing!

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