Diarrhea Home > Giardia in Drinking Water

You can often find Giardia in drinking water as a result of events such as sewage overflows, polluted storm water runoff, and agricultural runoff. In order to remove the parasite from the water, you need to boil it or use a specially recommended filter. Not all home water filters are effective for removing Giardia from the water. It's also important to have well water tested regularly.

An Overview of Giardia in Drinking Water

Giardiasis is a diarrheal illness caused by a very small parasite, Giardia intestinalis (also known as Giardia lamblia). Once an animal or person is infected with Giardia, the parasite lives in the intestine and is passed in the stool. The parasite is protected by an outer shell, which enables it to survive outside the body and in the environment for a long time.
In the past two decades, Giardia infection has become one of the most common causes of waterborne disease in humans in the United States (found in both recreational and drinking water). Giardia infections are more common in warmer climates, although they may be found worldwide and in every region of the United States.

How Does It Get Into Drinking Water?

Millions of Giardia parasites can be released in a bowel movement of an infected human or animal. Feces can then get into drinking water through different ways, including sewage overflows, polluted storm water runoff, and agricultural runoff.

How Can I Remove Giardia From My Water?

There are two ways to remove Giardia from your drinking water:
  • Boiling
  • Filters.
Boiling Water
Fully boiling your water for one minute (three minutes if you live in a high altitude) will kill or inactivate Giardia. Water should then be stored in a clean container with a lid and refrigerated.
Written by/reviewed by:
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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