At the core of urban water distribution, cast iron and ductile iron pipelines have been doing the same job for well over a century. Most people never think about them. The engineers maintaining them think about them constantly. Cast Iron: 1800s to 1960s Cast iron pipelines pioneered water distribution infrastructure in the 19th century. Wall thicknesses typically ranged from 0.5 to 1 inch, and initial design life assumptions of 40 to 60 years seemed conservative at the time.