Will salt tap or bottled water freeze faster?

The freezing rate in order of fastest to slowest would be: tap water, bottled water and then salt water. Although it's a toss up between bottled water and tap water. The more sodium content of a solution, the slower the rate of freezing. In fact, a supersaterated sodium solution has to have a temperature of -21 degrees Celsius in order to freeze. Any temperature above that, will cause the salt to melt the ice. That is why they use use salt on icy roadways in the winter. If the ambient temperature is below -21 degrees celsius however, ice on the roads won't help. So salt water would be the last to freeze. Why did I say tap water before bottled water? Bottled water usually, but not always, comes from natural springs. Although some people prefer this water over tap water, spring water can contain minerals, such as sodium (salt), calcium, which can slow the rate of freezing, unless the temperature is low enough. Tap water is wastewater that has been treated with chemicals (such as chlorine) and and filtered prior to it being sent to your home. The addition of these chemicals shouldn't slow down the rate of freeze and that's why I said it's a toss up between bottled and tap water. The difference in chemical make-up shouldn't interfere with the freeze rate, especially in a home freezer. Note that water at room temperature tends to freeze slighlty faster then cold water in a home freezer.