Summarizing the factors reported in the literature, this study built exponential models to express failures. Data of water-main breakage of Taipei city were used to develop the models. The results showed that the most significant factor affecting breaks of water distribution system is time, followed by the amount of water distribution, traffic, the length of pipe replacement, the length of pipes, and soil moisture. The results provide a decision-making reference for evaluating trends of water-main breakages.