Soil pipes are plumbing components designed to transport wastewater and sewage from toilets and other sanitary fixtures to the underground drainage system or septic tank. Typically made from materials such as PVC, cast iron, or clay, these pipes are crucial for maintaining hygienic conditions by effectively managing waste disposal. Soil pipes are usually larger in diameter than standard drain pipes to accommodate solid waste and prevent blockages, ensuring the efficient and safe removal of waste from buildings.