Lerrør

Lerrør, also known as earthenware pipes, are a type of pipe historically used for drainage and sewage systems. These pipes are manufactured from clay that is fired at high temperatures, resulting in a hard, durable material. The manufacturing process typically involves shaping wet clay into cylindrical forms, which are then dried and fired in a kiln. Once fired, the pipes are often glazed internally and externally to create a smooth, impermeable surface, which helps prevent leakage and facilitates the flow of waste.

The use of lerrør dates back centuries, with evidence of their application in ancient Roman and Greek civilizations for water supply and drainage. In more modern times, particularly during the 19th and early 20th centuries, lerrør were a standard material for municipal sewer systems in many parts of the world. Their advantages at the time included their relatively low cost, resistance to corrosion from the acidic nature of sewage, and availability of raw materials. However, they also presented challenges. Lerrør are brittle and susceptible to breakage from ground movement or heavy loads. The joints between pipes were often sealed with materials like bitumen or cement, which could degrade over time, leading to infiltration of groundwater into the sewer system or exfiltration of sewage into the surrounding soil.

Modern plumbing and drainage systems have largely transitioned to materials like vitrified clay pipe (VCP), which is a more advanced form of earthenware pipe with improved strength and reduced porosity, or plastic pipes such as PVC and HDPE, which offer greater flexibility, lighter weight, and easier installation. Despite being largely superseded, many older lerrør systems still exist underground, and their maintenance and replacement remain a significant undertaking for infrastructure management.