Cast iron sewer lines are very common. Today, when severe ground movement is likely, cast iron remains the material of choice. Although cast iron pipe, when installed properly, will provide a water tight seal; its propensity to rust and corrode often lead to many problems. Portions of the pipe may collapse allowing dirt to enter the line. Often, the pipe becomes perforated resulting in leaks. This provides water for thirsty roots.
When corrosion compromises a cast iron line, there are several options for repair. Unfortunately, although only a small portion of the line may leak, the condition of the pipe may be too weak to allow water tight repair. This may require complete replacement of the line. Furthermore, replacement of the line is often the best long term and economical solution.