The speed at which water freezes varies greatly from one situation to the next. However, there are some primary variables from which a general estimate can be formed. The temperature of the water and its surroundings are the most important factors when determining the rate at which water freezes.
Before water can freeze, the temperature surrounding it must reach 32 degrees Fahrenheit. This is why the environment in which the water is placed is the most important factor in determining the speed at which water freezes. Water placed in a colder environment will freeze faster than water of the same temperature in a warmer environment that is still below 32 degrees.