Giardia and Cryptosporidium
Giardia lamblia and Cryptosporidium parvum are protozoan parasites that are acquired through fecal-oral transmission and may be transferred from person to person due to inadequate hand washing after touching contaminated material or, less likely, through ingestion of contaminated food or water. We recommend that all members of a family be checked for Giardia or Cryptosporidium if one family member has the parasite, since infection does not always produce symptoms of diarrhea. Specimen collection kits from our laboratory are available through your family doctor.
If you suspect your private well water is contaminated with sewage or surface water, your drinking water should be tested for the presence of total and fecal coliform bacteria which are the main indicators of drinking water safety. If the laboratory test does not demonstrate total and/or fecal coliforms, Giardia or Cryptosporidium parasites are not likely to be present. If total and fecal coliform bacteria are present, indicating contamination from surface or shallow subsurface sources, remedial action should be taken to restore the structural integrity of the well and distribution system, followed by a shock-chlorination treatment. Assistance in restoring your drinking water to a safe level may be available from your local county health department, extension service or a reputable well driller.
Iron Bacteria Information
Iron bacteria, common in Iowa wells, pose no adverse public health effect but can plug filters, softeners and distribution lines. Presence of these organisms often contributes to obnoxious tastes and odors. Shock chlorination at levels of 50 to 100 mg/L in the well and distribution system may reduce their concentration to tolerable levels. These bacteria are thought to inhabit the water-bearing rock structure itself and have a tendency to move with finely divided particulate matter suspended in the underground water. Therefore, complete elimination is highly improbable. Continuous chlorination at 1 - 2 mg/L may retard their rate of growth but has not been demonstrated to effect their removal to any significant degree.