Construction of drainage structures
Sewerage of agglomerations: Works and special systems

The shape of drainage pipes is chosen on the basis of several factors, including expected flow rate, ease of construction and maintenance, and efficient use of space.

Small-diameter pipes are generally circular (see figure 1 ) because they are easy to manufacture, install and occupy minimal space, while minimizing the material required for their construction. The circular cross-section is also highly effective in resisting internal and external pressures. For these reasons, the circular shape is often preferred for domestic sewer pipes and other small drainage systems.