The simple and straightforward answer to this question is yes. Water pan is a really important component of an offset smoker which helps in many ways ranging from maintaining humidity and temperature to avoiding flare ups in smoker. Although it is a personal choice whether you want to use it or not if you want to get a good and crispy bark, then you can smoke in offset smoker without using water pan. although , you will have to keep an eye out for drying out of meat.