It’s often rumored that cold water boils faster than warm water. Although many have taken this as fact, the truth is, the warmer the water the faster it will boil. If you’ve ever wondered about this, the following information should put the question to rest.
The science behind boiling water is rather straightforward. The time it takes to heat a liquid depends on the difference in temperature between the liquid and the heat source. Therefore, warm water will reach the boiling temperature faster than cold water.
The belief that cold water boils faster than warm water is so common that you have to wonder where it came from. Well, one theory is that it was based on a misinterpretation. It's a little known scientific fact that under certain circumstances warm water will freeze more quickly than cold water. The facts were then twisted into a myth regarding warm vs. cold water and their boiling rates.
Another possible explanation for this old wives tale is the fact that using cold water for boiling is a legitimate recommendation for other reasons. Hot water will often have more sediment and impurities in it than cold water. This is because hot water has been sitting in a hot water tank and can leach substances from the plumbing. This was more relevant in the past when old pipes where in use.
Finally, cold water takes on heat more quickly than warm water. In other words, heated cold water moves to the point of being warm more quickly than it moves from warm to hot and from hot to boiling. There is a point of near boiling where this process speeds up again. Even though the first stage of the process is quicker, it’s still a longer process for the water to go from cold to boiling than from warm to boiling.
A Simple Experiment
If you are still not convinced that cold water will take longer to boil than warm water, why not conduct a simple experiment in your own kitchen? Fill 3 pots of the same size with water of varying temperatures, one with cold water, one with warm, and one with hot. Then simply watch to see which one is the first to reach the boiling point. Make certain that the burners have been set to the same level. Alternatively, you can boil one pot at a time and use a stop watch to calculate the time it takes for each pot to reach boiling.
You will soon come to the realization that hot water will be the first to reach the boiling point, followed by the warm water and lastly the cold water.
Faster is not Necessarily Best
Because of the possibility of more impurities in hot water, many chefs recommend using cold water for cooking. It might be worth it to wait the extra time it takes for the cold water to reach the boiling point if you want your food to taste the best it possibly can.