The use of cast iron pipes for plumbing and sewer systems started declining in the late 20th century as other materials with improved properties became more popular. While cast iron pipes were durable and commonly used in the past, they had some limitations, such as susceptibility to corrosion over time and the heavy weight, which made installation more challenging.
The specific time when cast iron pipes were entirely discontinued varies depending on the region and local building codes. However, in general, their use significantly decreased in the 1970s and 1980s. By the 1990s, most new construction and renovation projects shifted to alternative materials like PVC (polyvinyl chloride) and ABS (acrylonitrile butadiene styrene) pipes, which are more resistant to corrosion, easier to install, and less costly.
While cast iron pipes are no longer widely used in new construction, some older buildings and infrastructure might still have existing cast iron pipes in place. In these cases, ongoing maintenance and inspections are necessary to ensure the pipes are functioning correctly and to address any potential corrosion or deterioration issues.