Trimee, welcome to SMF! Glad you are here and asking questions right out of the box.
Let us know what brand of water bullet smoker you have. A lot of folks here, me included, use the
Weber Smokey Mountain, so we have some experience with bullet smokers.
First, understand what is happening inside a bullet smoker. When it is empty, no meat or water, the energy from your fire will heat up the air flowing through your smoker from the bottom vents to the top. When you add cold water and cold meat, it is like adding a heat sponge. The technical term is "heat sink." The cold water and meat absorb the available heat, dropping the chamber temp of your smoker. Planning for this temperature drop is part of the process of prepping your smoker.
A gallon of water weighs 8.34 lbs, or 3.78 kg. That's a big heat sink. My
WSM hold 3 gallons of water. I can heat my smoker dry to 350F, then throw 3 gallons of 70F water in in, and watch the chamber temp drop like a rock as the water starts absorbing the heat. I dry smoke, no water, for just that reason.
Water is meant to be a temperature stabilizer. With three gallons of water in my smoker, I will see the chamber temp eventually rise to 200-215F. The issue is I'm using fuel to heat water. To me, that's a waste of fuel. I'd rather be heating meat, that's why I dry smoke. Learning to control your chamber temps with the bottom vents is all part of the fun of learning to use your smoker.
Try a dry smoke with your smoker and you'll see different temps.