Abstract: A water-tight fiber optic ribbon communications cable constructed without the use of gel or grease in the buffer tube(s) thereof. A plurality of water-blocking yarns are provided around at least a portion of the stack of fiber optic ribbons loosely positioned within the buffer tube(s) that possess water swellable characteristics. The swell capacity of the plurality of water blocking yarns exceeds the critical mass of water that could enter the buffer tube(s) by a factor of 2.0 or more. Optionally, superabsorbent powder can be applied between and/or on the fiber optic ribbon stack.