HAV is the most common cause of viral hepatitis worldwide, infecting millions of people each year. The HAV is transmitted mainly from person to person through the feces of infected people in person-to-person contact or through contaminated food and water. There is a direct and close relationship between the prevalence of hepatitis A infection in each community and the health status, access to safe drinking water, and socio-economic status of those communities. Materials and Methods: In April 2017, two definite hepatitis A cases were reported by an infection prevention and control specialist at Sina Hospital, Karun County. A case-control study was performed to identify the risk factors for the disease. A questionnaire of possible risk factors for the disease was then prepared. Independent variables were water consumption from desalination plant No. 1 (Mr. Zubeidi), water consumption from desalination plant No. 2 (Mr. Zahiri), history of vegetable consumption, history of swimming in Karun River, history of contact with patients, travel history, gender, and age. The required data were collected and then imported into SPSS software. They were then analyzed through logistic regression. Results :The logistic regression analysis results showed a relationship between hepatitis A and water consumption from the desalination plant No. 1 (Mr. Zubeidi), adapted to other variables (p-value = 0.01 and OR: 11.6). Furthermore, there was a relationship between hepatitis A and water consumption from the desalination plant No. 2 (Mr. Zahiri), adapted to other variables (p-value = 0.00, OR: 0.03). Conclusion: Patients with hepatitis A bought drinking water from Mr. Zubeidi desalination plant 11.6 times the healthy people. Our study also showed a significant difference and a negative relationship between drinking water consumption from desalination plant No. 2 (Mr. Zahiri) and the hepatitis A outbreak in Ismailia.