10 ft. x 6 in. Flood Barriers. Large-sized water barriers for flooding activate upon contact with water, swiftly forming heavy-duty barriers to effectively block, control, and separate floodwaters, safeguarding homes and property. Upon contact with water, they swiftly expand to form a sturdy 3 in. to 4 in. heavy-duty barrier. effectively blocking floodwaters to protect your home, garage, and basement.