In the mid-1800s, physician John Snow recommended removal of the handle from a water pump in a London neighborhood, ending an outbreak of cholera that had killed more than 500 people in a 10-day period. In the past 150 years, much progress has been made in understanding and preventing the transmission of infectious waterborne diseases. Even so, waterborne pathogens continue to be transmitted to humans via recreational water contact and contaminated drinking water supplies throughout the world, resulting in morbidity and mortality that is preventable. Infections that result from contact with waterborne pathogens can result in either endemic or epidemic disease. Most waterborne diseases are endemic in a population—there is some baseline level of disease that occurs normally in a population. An epidemic is defined ...