Cast iron pipes were commonly used in residential plumbing systems from the late 19th century to the mid-20th century. The specific year when houses have cast iron pipes can vary depending on factors such as location, construction practices, and renovations. Many older homes built before the 1960s may still have some sections of cast iron piping in their plumbing systems. However, it's important to note that cast iron pipes have been largely replaced by more modern materials like PVC (polyvinyl chloride) and ABS (acrylonitrile butadiene styrene) in newer constructions and plumbing renovations. If you're concerned about the plumbing in a specific house, it's best to consult a professional plumber or conduct a thorough inspection to determine the type of pipes used.