The word "tub" do you mean the bath tub? "drains seem to be smooth", what does this mean? Have you checked the union of the tank to the bowl? There are two nuts that will tighten this, but, do not ratched down on them as you will crack the porcilen. Then check the overflow valve, is the water creepint too close to the top of the tank? Then last, have you added to the height of the flooring? If so, did you add an extension to the flange? Did you install the wax ring up side down? Put a level on the floor area and does the comode sink into a small concave area? If so, you also might have a leak in the pipe around the tub and the water is "ponding" around this area.