A cistern is a waterproof receptacle used for collecting and storing rainwater or other liquids. They are often found in areas where water supply is limited, serving as a crucial resource for drinking, irrigation, and sanitation. Cisterns can be made from various materials, including concrete, stone, or plastic, and can vary in size from small household units to large underground tanks. Historically, cisterns have been used since ancient times, with notable examples found in Roman aqueduct systems and Middle Eastern architecture. They play an essential role in water conservation, especially in regions facing drought or water scarcity, by capturing and storing rainwater for future use.