In August-October 1980, a sudden increase occurred in the number of cases of jaundice reported among residents of a rural, agricultural section of Lancaster County, Pennsylvania. Investigation confirmed the cases as hepatitis A and showed that the outbreak was associated with consumption of water from a water fountain in a hardware store and water from the adjacent family home, both of which came from a well contaminated with feces. A total of 49 cases occurred from August 11 to October 21 in store customers, employees, family members, and persons visiting the family residence. Unusual features of the outbreak included an epidemic curve with two peaks, a very high attack rate in susceptibles at highest risk (greater than 90%), a high proportion of cases with jaundice (85%), absence of asymptomatic cases, and a high male to female ratio due to the makeup of the group at risk.