I loathe room temperature water, and even worse, warm water when the bottle has been left in a hot car. I was a bit sceptical but I am so impressed with this bottle. My chilled water has stayed chilled on the car, and a bottle in the bedroom was still chilled the following day. Our kitchen tap delivers filtered chilled water, so this is colder than general tap water, which may help. It doesn't get condensation on the outside either, so has been perfect to carry around in my handbag too. I'm very happy!