Sewers are underground systems designed to transport wastewater and stormwater away from urban areas. They help prevent flooding and protect public health by carrying waste to treatment facilities. Sewers are typically made of materials like concrete, clay, or plastic and can vary in size depending on the volume of water they need to handle. The sewer system is an essential part of urban infrastructure, often connected to drains and manholes for access and maintenance. Properly functioning sewers reduce the risk of contamination and environmental damage, making them crucial for maintaining clean and safe living conditions in cities.