To be sure I always have cool or cold water I carry at least two insulated bottles. One is semi-frosty from sitting overnight on the top shelf of the fridge under the cold air vent from freezer. It'll have some frost but not frozen solid. It'll stay cool for the 60-90 minutes it takes me to drink it.
The second bottle is frozen solid overnight. By the time I've finished the first bottle the second is thawing and will stay cold for a couple of hours. Depending on my route I'll stop at a convenience store to refill with a bottle of generic sports drink poured into the remaining chunk of ice in the second bottle.
If I'm not sure about supplies on a route I'll take a third bottle or Mylar pouch, also frozen, in a jersey pocket.
I also have a double insulated stainless thermos that fits my water bottle cages. Sometimes I'll fill it about 1/2 to 2/3 full, freeze it, and top off with plain water. It'll stay icy 12-24 hours depending on ambient temperature. Or I'll fill it with hot coffee for winter rides. It's heavy but worth lugging for really hot or cold rides.