Who needs to take special precautions with drinking water?

People with immune systems weakened by AIDS, chemotherapy, or transplant medications are likely to be more vulnerable to contaminants in drinking water, such as the microscopic parasite Cryptosporidium. Boiling the water kills this parasite. Some bottled water has already been treated to protect against this germ. (Check the label on the water bottle to be sure.)
 
Those with weakened immune systems should remember that they can be exposed to water-borne pathogens not only from the water they drink but also from water used for brushing teeth, making ice cubes, and washing fruits and vegetables.
 
Source(s):
EPA Water Health Series “Bottled Water Basics”