Today, vast networks of sewer pipes are buried underground all across the globe, providing sanitation to virtually every modern city and town. Modern sewer pipes are made from a variety of durable, 

corrosive-resistant materials that can last 50-100 years or more. For some pipes installed within the last few decades, their true, practical lifespan is unknown because they have not had enough time yet to need replacement. But it took thousands of years of improvements in material science, as well as ever-changing needs from society, in order to drive the innovation that led from the earliest sewer systems to today’s.

The earliest known people to create an urban sanitation system was the Indus River Valley civilization. In the city of Harappa, located in modern-day Pakistan, vitrified (fired) clay brick pipes and simple gravity-fed cesspits were employed to deal with wastewater. Archaeologists estimate this site is around 4,500 years old, perhaps older. Clay piping is resistant to corrosion, and the preserved examples that have lasted through to today are a testament to their durability. Although the concept is old, clay is not outdated and still retains relevance for pipe construction even in the 21^st century, using modern firing and glazing processes. However, newer pipe materials have superseded their former widespread usage, and they are less common than they were in ancient times.

Over 2000 years later, the Greeks and Romans were still using primarily clay brick and stone for piping. At this point, cities were not particularly dense, nor did the pipe makers possess the advanced material science necessary to make use of different materials. However, they were able to construct more sophisticated systems including pressurized water piping, water siphons, and aqueducts. One difficulty when constructing clay piping is that the raw material is very heavy and difficult to transport, making it impractical to construct extensive clay pipe sewer systems in places with no nearby source of natural clay. In places where clay was hard to find, hollow trees were sometimes used, although they were not as common, and clay remained the dominant material for thousands of years.

The first major use of metals in pipe construction was in the construction of wooden stave pipes. Although cast iron had been produced by blacksmiths in Africa and Asia as early as the 5^th century, it was not until the 15^th century when it was introduced to Europe. As Europe began colonizing the Americas, the abundance of wood led to the development of wooden stave pipes. Like a barrel, many thin wooden staves are braced in a cylinder using iron rings. The first wooden stave pipes were used in Boston in the 1650’s, and although rare today, can still be found in some applications. Shortly afterwards, the first cast iron pipes were developed for use in France.

With the industrial revolution came the challenge of high-rise buildings, and cities more dense than had ever been seen before. Much more complex and extensive sanitation systems would be needed, and it was during the 19^th century that fiber pipes came into use. Fiber pipes were sometimes known as “Orangeburg Pipes” owing to much of the manufacturing based in Orangeburg, New York. First implemented in Boston in 1867, fiber pipes use a mixture of compressed wood pulp, tar, and other materials to create an inexpensive and lightweight pipe. Fiber pipes were seen as a cheaper alternative, and are no longer used, primarily due to their poor durability, not to mention that many contained asbestos.

In the past 50 years, many new materials have been utilized for piping and continue to be used today. Concrete piping, galvanized steel piping, cement-lined cast iron piping, ductile iron piping, and various types of plastic piping, in particular PVC, or polyvinyl chloride, are among the most common materials. Compared to the various types of pipes created in the past 500 years, these new types are cheaper and easier to manufacture, more resistant to corrosion, longer lasting and more durable, and contain little to no hazardous materials in their construction. However, the one pipe material that has truly withstood the test of time is the reliable clay pipe, still being laid today as it was thousands of years ago.

Written by Eli Lord