You should replace your pipes as they approach the end of their typical life span, or if they are experiencing frequent leaks and problems. The life span of popular residential pipes is as follows: PVC: At least 100 years PEX: At least 50 years CPVC: 50 to 75 years ABS: About 50 years Copper: 50 to 100 years Galvanized steel: 40 to 100 years Cast iron: 50 to 100 years