What happens if I drink water that contains viruses, bacteria and protozoa?

First, it will usually take more than one organism to make you sick—around 10 for protozoa and viruses and 10 to 1,000,000 for bacteria depending on the species. The onset of symptoms can start anywhere from 10 hours to several weeks from the point of infection depending on the type and amount ingested, and constitution of the individual. Symptoms can range from nothing to diarrhea, abdominal cramps and pain, nausea, vomiting, muscle cramps, fever, fatigue, headache, chills, loss of appetite, and, in the case of hepatitis, dark urine and jaundice. Symptoms usually dissipate in a couple of days or weeks, again depending on the three elements above. Healthy adults will generally knock the illness without needing medical attention and without lasting effects. However, infants, young children, elderly, pregnant, and immune-compromised individuals are at higher risk of needing medical attention or having complications from an illness. Your location—a remote basecamp in Pakistan or a day hike close to home— will play a key role in the severity of your illness, should you become infected. For more information on diseases caused by specific pathogens, please visit www.cdc.gov.