How can I effectively use an immersion water heater for my bathtub to ensure a comfortable and relaxing bathing experience?

To effectively use an immersion water heater for your bathtub, fill the tub with water to the desired level before submerging the heater. Turn on the heater and wait for the water to reach your preferred temperature. Stir the water occasionally for even heating. Once the water is warm enough, turn off the heater and enjoy a comfortable and relaxing bath. Remember to follow safety precautions and never leave the heater unattended while in use.