If you top up your Hydro Flask and then just throw in 2-3 ice cubes, these ice cubes melt very quickly. As long as the water is still relatively cold, it is still OK to drink as there is nothing wrong with cold water. In my article on what to do if your Hydro Flask gets a dent, I talk about Hydro Flask’s lifetime warranty. While hydro bottles shouldn’t lose their insulating capacity over time, this may be the perfect excuse for you to upgrade your hydro bottle and get the new size or color you want.
If you fill your Hydro Flask with a good amount of ice and then fill it with cold water (not room temperature water) and don’t expose your bottle to extremely hot temperatures, you should easily get more than 24 hours of ice retention from your Hydro Flask.