Accidental water pollution and rapid diffusion of the pollutant terribly affect water quality in the distribution network; the consumers complaint information to water utilities is an important way for monitoring the condition of the water supply systems timely where there is lack of monitoring station. The research first uses the location information of consumer complaints to find the candidate pollution source nodes through the improved pollution matrix methodology. And then the probability of each candidate pollution source node is calculated on the basis of the total probability formula and evaluated by Borda Count and Normalization Count to identify the most possible pollution source. The feasibility and effectiveness are verified through a source contamination event in a city.