Stay Warm and Comfortable During Winters With Immersion Rod. Immersion water heating rod is a simple appliance that uses a heating coil and a cord (like that on an electric iron) to heat water. Once plugged in current, the element starts to heat up and thereby, heats water. All you have to do is fill the bucket with water and dip the rod in it to heat. Depending on the volume of water, it takes a few minutes for the immersion rod to heat water. The latest versions come with a clip to fix the rod at the hem of the bucket or utensil used and an indicator to make the process easier.