Abstract: A fluid-fillable barrier includes a tubular, impermeable membrane and at least one tension member. The membrane has a first attachment area and a second attachment area. The tension member secures between, and extends from, the first attachment area to the second attachment area. When in tension, the tension member may pivot with respect to the membrane, and has a taut length which is less than one-half of the perimeter of a cross section of the membrane, the length and perimeter being measured at a common cross-section taken perpendicular to a longitudinal axis of the membrane.