Is your well in a rural area where animals graze? Well water can become contaminated with feces if animal waste seepage contaminates the ground water. This can occur if your well has cracked casings, is poorly constructed, or is too shallow.
Tests used to specifically identify Giardia are often expensive, difficult, and usually require hundreds of gallons of water to be pumped through a filter. If you answered “yes” to the above questions, consider generally testing your well for fecal contamination by testing it for the presence of coliforms or E. coli instead of Giardia . Although tests for fecal coliforms or E. coli do not specifically tell you whether Giardia is present, these tests will show whether your well water has been contaminated by fecal matter.
These tests are only useful if your well is not routinely disinfected with chlorine, since chlorine kills fecal coliforms and E. coli . If the tests are positive, it is possible that the water may also be contaminated with Giardia or other harmful bacteria and viruses. Contact your county health department, your county cooperative extension service, or a local laboratory to find out who offers water testing in your area. If the fecal coliform test comes back positive, indicating that your well is fecally contaminated, stop drinking the well water and contact your local water authority for instructions on how to disinfect your well.