We have not tested rehydrating our meals with cold water. While it should work, it could take upwards of an hour to fully rehydrate the meal. The flavors also may not be as bold, as the boiling water cooks the ingredients for the first time. Some of our long-distance hiking friends like to hydrate in the morning for their mid-afternoon meal, but you’ll have to experiment on your own! Always remember, once hydrated, these meals should be treated with the same care as any other prepared and fresh food. For best results, we always recommend following the directions on the back of the pouch.