Illness is possible, especially for people that already have a chronic illness or may have compromised immune systems, for example, from AIDS or cancer treatments. This is why boil water notices are issued. Anyone experiencing symptoms such as diarrhea, nausea, vomiting, and abdominal cramps should seek medical attention. These symptoms (with or without fever) are not always due to contaminated water and a doctor's assessment and medical testing are key to identifying the cause of illness.