A method of determining optimal repair options for cast iron and ductile iron water or wastewater pipe sections having a number of pipe-lengths is provided. The method includes the computer-implemented steps of inputting measured pipe-length wall dimensional data, determining pipe failure rates for current and future times based on the input data, defining one or more repair scenarios for the pipe, and determining the pipe failure rates for the defined repair scenarios. The pipe failure rate determinations are provided to the user as an output. The calculation of failure rates includes determining probability of pipe-length failure due to corrosion and determining probability of pipe-length failure due to transverse bending.