Rainwater is a key indicator of global pollution, with elevated concentrations of hazardous elements (HEs) often linked to factors such as traffic, port activities, and marine industries. Acid rain forms when atmospheric gases—primarily carbon dioxide, sulfur dioxide, and nitrogen oxides—react with water in the atmosphere or on the ground, transforming into acidic compounds. Oxidants play a significant role in many of these acid-forming processes. The composition of rainwater can also impact the preservation of cementitious building materials. In regions affected by salinity, high fluoride levels, or pollution, rainwater can be the most reliable source of domestic water