how long dose the water stay cold?
All I remember was it was better than not having it. That and during colder weather, the tube did not freeze like everybody elses did that had a water bladder The mouth piece froze, but all I had to do was keep it in my mouth awhile and it worked fine after awhile. Because I decided to reduce my pack weight, I no longer use the insulation portion. I could test it if you like.
That depends upon how warm it is outside and how much water is in the pack (thermal mass). The insulation is pretty thin, so I wouldn't rely upon it for a super-cold drink hours into a hike, but it will be ok.
For several hours if not in the direct sun (ie on front seat of auto). During the summer in back pack at the beach fishing for most of the day.
I use it at work for a 12 hour shift. I fill it with ice and water and it is still cold when I get off. Even locked up in the sun in the middle of summer it does a great job staying cold.
I have placed a frozen bottle in the morning of a backpacking trip, hiked all day in 90 degree weather and still have had ice at the end of the day. makes it nice when i refill at the end of the day before bed and i still have some ice in there to cool the new water. it does sweat, though.
I've never measured an exact time frame. Nor would there be much of a point seeing as it is dependent on the outside temperature, exposure to direct sunlight, intensity of said sun and so on and so forth.
I can only give my subjective opinion that it does a pretty good job of keeping cold water cold.
I fill it with ice and a little water and it stays cold all day.
I love it.
On average, a few hours.