5 hours and I start with the bottles full of ice and water and by the end on my ride the second bottle still keeps my water cool
341325
I use two of theses bottles on my road bike. I ride for about 2.5 hours and I start with the bottles full of ice and water and by the end on my ride the second bottle still keeps my water cool. I ride in Florida and it can get very hot.  I would most definitely recommend this Water Bottle. Great Product.
4611601
I absolutely LOVE my Hydro Flask. I live in Tucson, so it's vital to bring water with you when you go anywhere, especially in the summer. I put some 2" ice spheres in it, and it keeps my water cool for longer than the 24 hours. With the bigger ice cubes that I use, there's still a decent amount of ice left in the bottle after 24 hours. I don't think I could ever go with a different water bottle after using this one again.
4623744
Ok, so I read a few reviews. I wanted a bottle that held abit of water and this does that. What I really wanted was a bottle that would keep my water cold for a long period of time, 4 to 5 hours. What I got was a bottle that does alright, I'm not wowed like other people who purchased this in the phoenix, az. Area. It is summertime here and today's temp was 108. I feel the bottle with ice and topped it with water. We went to an area about an hour way from us and by the time we got there it was still cold and ice about half melted, we were in a new air conditioned car. Another hour or so the ice was melted and water still cold. I did notice this unit is really cold on the outside which I would think should not be if it is insulated good. My wife has a cheap one from Walmart and hers is not cold on the outside. I like everything about it except the fact it keeps stuff cold for only a couple hours......
4228383
I use this to carry ice on long bike rides. Holds ice for more than 24 hours in 90F weather!!!!!!
Fits in to the water bottle cage of my bicycle. A little tight, Not the lightest insulated water bottle, but nothing holds ice longer.
2082495
I live in a very hot climate and wanted something that would keep my drinks cool for hours while I ride my bicycle and hike. It was over 100 degrees the other day and my water was still cool after several hours.  The insulation is great!

On the other hand, the bottle is slightly bigger around than most water bottles that go into bottle cages on bikes.  If you have metal cages and you can pull apart  the cage arms slightly, it will fit fine.  I was able to get the bottle in both of my metal cages.  But, if you have plastic cages, you might have problems. It will probably fit, but the fit will be so tight you'll have problems getting the bottle out of the cage while on the move.
2534986
OK so it's not that I can get super excited about a water bottle.  I tend to cramp up if I don't drink on long rides.  I carry two of these bottles and they last me at least 3 hours on a hot day.  The first thing I did was get rid of the blue band around the top.  You don't need it.  These bottles are also very leakproof as long as you have the rubber ring inside the top.  My only criticism is that they are a little harder to squeeze but I guess that's a tradeoff.
314830
I put ice in my water in the morning and at night there is still a lot of ice still in the bottle.
4754122
My water stays cold for the whole day. The fluids have so far stayed a similar temperature to when they initially were put into the bottle. I also like that the bottle is skinnier than some of my previous water bottles. It fits in cup holders better. Overall, I just got this water bottle and I really like it.
1338958
All of the reviews are true. This is one amazing water bottle. I prefer to drink water that is super cold and this bottle does the trick. I put ice in the night before and well into the next day there is still lingering ice. Even when I had put less ice, the water remained cold for at least 12 hours. Amazing!

My only complaint would be the lack of a straw or better way to drink from the flask. However, it does not affect the overall performance.
1206792
I am very picky about my water bottles, so it definitely takes a lot for a new bottle to impress me. The Coldest Water bottle has done that. I have not tested the accuracy of the product name ("The Coldest"), but as far as I'm concerned, it has done its job and done it well. First, it is sturdy and not cheap feeling. It is too early yet to tell whether the outside of the bottle will hold up to my daily usage, so I will try to post an update later. As for keeping my water cold? Yes, I'm happy to report it has done that. I fill it with ice and cool water in the morning and continue topping it off throughout the day. The next morning, there is still ice in there and it's still pretty cold. The top that comes with it feels sturdy, but I wanted a more convenient way to drink my water; so I purchased the separate straw top (a little pricey at $9.99 in my opinion). I do like the straw top as it makes it much easier to drink from a reclined position. I hope this bottle will hold up the way my Zojirushis and Kleen Kanteens have and I look forward to testing it under the blazing heat of a good old California summer!
75591
I fill my bottles with ice and water to sip on through out the day; the ice still fits though the wide mouth, but doesn't sloshing up and soak you when you're drinking later.
4183918
This water bottle holds a lot of water and keeps it cold all day! I don't put ice in mine, just cold water from my frige and it stays just as cold as when I  fill it up in the morning. I work outside in the desert where temps in the summer reach over 110 degrees and it's necessary to have cold water. I found another water bottle early on and really liked it but now can't find it anywhere so I thought I would try thermo tank. I didn't think I would be able to find anything as good as my last bottle but thermo tank has proven to be just as good if not better.  It holds more water than most bottles and it has a great design. I especially like that the drinking area isn't so big so you don't get a deluge of water spilling out everywhere when you try to drink.
4250712
I love these - I have 2! Put ice water in one day and it's still colder than tap water 24 hours later, not that I typically let water sit in it that long - the idea is to drink it, after all! I particularly like the outer coating, which nicely resists scratches and dings and keeps the bottle looking great, even after banging around in the outer mesh pocket of my backpack every day.
427858
I love these bottles!  They keep the ice and water I fill them with each morning cold throughout the entire day and they still have ice in them at the end of the day.  As a person who enjoys their water ice cold, they have helped me greatly increase my water intake.  I'm so glad I purchased these!  I'll be purchasing additional bottles for my daughter for the soccer season.
4431267
So far this is one of my favorite backpacks the water still cold after riding my bike for several hours on a 80 degree temperature. I love it!
3917296
It's not an exaggeration that this water bottle keep ice frozen for HOURS. I can put ice cubes in at the beginning of my day at 7:30am, and by the time I get home at 5:30, I still have ice. I'm the type of person who need my water to be ice cold. This bottle has definitely help in rea my water intake. I got a 32oz bottle for Christmas which is even better because I can stuff it with even more ice. I bought the lid with the pop out straw and it's worked excellent. I'll never got back to plastic water bottle where the ice melts in five minutes.
713117
I did a test, froze water bottles, just filled the bottom and went to the lake 2 days, filled it with various things like shrimp and fish during the trip all bottles were still frozen when I got home, very good cooler