a portable , water - filled barrier is internally divided into cells and emulates a sandbag dike or wall without requiring sand or intensive labor to install . a rigid ladder spans the barrier to provide structural support and enable traversing of the barrier . the ladder can be attachable to the barrier . the light , flexible barrier material can include nanofiber . automatic valves can seal openings between the filled cells , so that a punctured cell will not cause cells below and behind to deflate . cells can project below the base into a stabilizing trench . cells can include internal or external rods or plates that support the barrier structure . some embodiments can be initially filled with air , positioned , and then filled with water while the air escapes through a pressure valve . other embodiments are filled from above , and inflate and deflate without allowing air into the barrier . barrier end structures can enable interlocking of adjacent units .