Shigella is the group of bacteria that causes Shigellosis, one of the most contagious types of diarrhea caused by bacteria. Most individuals with Shigellosis experience diarrhea, fever, and stomach cramps although some will have no symptoms but may still pass it onto others.

Although Shigellosis can be caused by drinking water, it is more often associated with water recreation as individuals often swallow untreated water accidentally. Wells can be contaminated with Shigella by sewage overflows, improperly maintained sewage systems, and polluted storm runoff. Wells are particularly vulnerable to Shigella contamination after a flooding event, especially if the well is shallow, a dug or driven (bored) well, or submerged under water for a long time.

If you suspect your water is contaminated, contact a state certified laboratory about getting your water tested.

Shigella may be killed or inactivated by bringing the water to a rolling boil for one minute (longer in higher elevation). It should then be allowed to cool in a clean, sanitized container with an air-tight cover and refrigerated.

Short-term disinfection solutions include ultraviolet light-based instruments, which inactivate bacteria, and iodine tablets, which are often used for camping. However, iodine tablets do not kill all pathogens and should only be used on an emergency basis.
If you are on a private well, a long term option is well disinfection.  If you would like to disinfect your well, contact your local health department.