To smoke a hookah, start by filling the water container so that approximately 1 inch of the bottom of the stem is submerged. If there is not enough water in the water container, the smoke will not filter through enough water and may become harsh. If there is too much water in the water container, it will be more difficult to draw the smoke through the hookah. Try some different water levels out on any new hookah to get a feel for the right amount of water to use. Tobacco is then placed in the bowl at the top of the hookah. The tobacco is then covered with perforated tin foil or metal screen and a coal is placed on top. Then someone inhales smoke through the hose, which draws air over the coal and through the bowl. The hot air from the coal evaporates the tobacco, instead of burning it. Smoke is thus produced and travels down the stem into the water in the water container. The smoke then bubbles up through the water into the top of the water container where the hoses are attached.