Sandbags are used to prevent levee failure, redirect river currents and construct dikes or other water barriers. The bag itself is usually made of burlap, canvas or polypropylene. Although clay and soil can be used in sandbags, sand is preferred because of its natural ability to absorb and hold water. Sandbags become heavier when wet, which works to establish watertightness in dike construction.
Hold the bag open while another person shovels sand into the bag. Fill the bag halfway. Do not add more sand, as it will not help. Filling the bag halfway with sand allows the bag to be moved more easily. Be sure to wear gloves, plus goggles to protect your eyes from the sand.
Close the top of the bag. Scrunch the walls of the bag together like a candy bag.
Tie twine or a plastic tie near the top of the bag. Do not tie close to the sand because the sand needs room to move within the bag. If sand fills more than half the bag, do not tie the bag. Empty the bag so only half is filled with sand, then tie at the top.