A boil water advisory is issued whenever pressure in the main water line drops below a certain amount established by the Louisiana Department of Health and Hospitals; it then becomes possible for material to enter the water main potentially impacting water quality.  A boil water advisory is issued as soon as the SHMO water system determines that pressure in the system has been lost.  As soon as the repair has been made and the main has been pressured back up with water, samples will be collected and analyzed by DHH.  The boil water advisory is lifted when the results from DHH shows "all clear."  (Note that there can be other reasons for a boil advisory but loss of main line pressure is most common.)

"Click" on the document below from the Centers for Disease Control Prevention regarding what you should do during a Boil Advisory.