This study aims to assess the impact of Water, Sanitation, and Hygiene (WaSH) insecurity on the health of displaced populations and identify key factors associated with the spread of infectious diseases. A mixed-methods approach was employed, including both quantitative and qualitative components. The quantitative component involved a cross-sectional survey of 1,500 displaced persons across five Gaza Strip governorates from 3 April to 6 August 2024. The sample size was calculated to ensure statistical significance and representativeness of the population. Data on the incidence of infectious diseases were collected and adjusted for the sample size. The qualitative component included in-depth interviews and focus group discussions with a subset of participants to gain insights into their experiences and coping strategies. The quantitative analysis revealed high incidence rates of various infectious diseases among the displaced population. Diarrhea and acute respiratory infections were the most prevalent, with incidence rates of 24.9 and 49.3%, respectively. Other significant findings included rates of skin rash (3.7%), scabies (2.5%), and acute viral hepatitis (5.6%). Qualitative data highlighted severe WaSH-related challenges, including inadequate access to clean water and sanitation facilities. Participants reported widespread health issues, psychological distress, and resource scarcity.