Shigella and Drinking Water from Private Wells

What is shigellosis?

Shigellosis (shi-ghel-O-sis) is an infectious disease caused by a group of bacteria known as Shigella. Shigellosis is one of the most contagious types of diarrhea caused by bacteria. It is a common cause of waterborne outbreaks in the United States, though most of these outbreaks occur in recreational water rather than in drinking water.

For more information about shigellosis illness and treatment, please visit CDC's shigellosis page.

Where and how does Shigella get into drinking water?

Shigella is found in every part of the United States and throughout the world. The bacteria can get into groundwater and private wells through discharges from faulty septic systems or sewage treatment plants. Wells may be more vulnerable to such contamination after flooding, particularly if the wells are shallow, have been dug or bored, or have been submerged by floodwater for long periods of time.

How can I find out whether there is Shigella in my drinking water?

If you suspect a problem and your drinking water comes from a private well, you may contact your state certification officer for a list of laboratories in your area that will perform tests on drinking water for a fee.

How do I remove Shigella from my drinking water?

Heating water at a full boil for 1 minute (3 minutes if you live in a high altitude) will kill or inactivate Shigella. Other short-term options for purifying drinking water that has been contaminated with Shigella include using a filter or an ultraviolet light-based device designed to remove or inactivate bacteria in drinking water. Water may also be treated with iodine tablets, such as those intended for use while camping. However, iodine-based treatments do not protect against certain germs like Cryptosporidium, and they should be used only on a temporary or emergency basis. Regardless which water purification method you use, you should store the treated water in a clean container with a lid inside the refrigerator.

Disinfecting your well may be a longer-term solution. Contact your local health department for recommended procedures. Have your well water tested regularly, at least once a year, after treatment to make sure that the problem does not recur.

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