We have 2 Yeti's and a Tal, both SS lined. Neither has failed. All 3 can keep ice, ice, overnight. I'd throw one out if it stopped working and just buy another one. They're not that expensive...like..$20 for a Tal. Walmart carries them.

We need more info. Is it stainless steel, plastic, double walled, does it have a seal, a straw, or a see-through sliding closure (the least effective)? Lots of things to consider. A good tumbler will likely keep beverages cold longer than hot. I have half a dozen that I really like. Contigo West Loop Autoseal. And I'm waiting for another to arrive on Thursday. Here's the link - https://www.amazon.com/dp/B07HHTSRJ7?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_2&th=1

As long as you push the seal it is open. When you let go, it automatically seals.

You don't put them in the dishwasher do you? They are typically not dishwasher safe. I have had mine for years, it came from Walmart. I also have a Contigo that I use if I'm taking coffee somewhere, it's many years old too.

Does it hurt if you put soda in it? I usually don't, but maybe I did, and it messed it up. I ordered another one yesterday.

We have ones that are stainless steel inside and out, and they keep ice water cold for days. I've never put soda in them, but I would think it would be okay, although there is the risk that it would go flat. I always fill them with ice before adding water - I do not know what brand we have. Our real estate agent gave us some new ones with our names engraved on them.

I agree more details would be helpful.

If they're plastic, might the seal have been broken or separated somehow? Sometimes there's a hairline crack that's not obvious.

I use stainless steel bottles too, and when I had plastic insulated tumblers (for my mom), I hand washed them only.

What kind of tumbler? A dollar store tumbler probably won’t work as well as a Yeti.

Back in first grade, my parents were traveling and the babysitter let me pack my own lunch. I put soda in the thermos instead of milk. Carbonation plus shaking around -- when I opened my thermos, Coca Cola exploded all over me. Lesson learned. I would NOT put soda in a tumbler unless it was just going to sit in one place and not be carried around.

If you’re asking about the newer types of stainless steel water thermos bottles, we have a couple of 32 oz Hydropeak Nomad bottles We fill them with water and icecubes and they keep the water cold & fresh for over 24 hours. Stainless steel lined. They do not leak.

The exterior finish stays clean and pretty. We wash them by hand.

If I were going to want cold soda, I’d put ice in the thermos. Keep the unopened soda in a separate cool area.

I've had carbonated water cause issues with one of my stainless water bottles - I think the internal pressure made it leak. I don't put anything carbonated in them any more.

OH yeah, I suppose if the container is air tight then the carbonation could mess it up from the pressure. I didn't think of that because the one I use mostly is not air tight but it does keep my water ice cold even until the next day if I have any left over. So yeah, if yours is air tight like the Contigo type, carbonation would not be good for it.