Impacts of cathodic protection on pipe break probabilities: a Toronto case study

The pipe break database of the Greater Toronto Area (GTA), dating from 1960, is used to quantify the impacts of cathodic protection (CP) on the frequency of pipe breaks. The findings demonstrate that the average time between pipe breaks increases by up to an average of almost 4 years for ductile iron pipes after CP is placed on a pipe. Further, the probability of a pipe break occurring 10 years after the application of CP decreases in comparison with pipes that have not been cathodically protected. The cost savings for CP are substantial, with the repair costs (including the cost of CP implementation) decreasing to one-third for ductile iron (DI) pipes of 150 mm diameter and to one-half for DI pipes of 300 mm diameter. The cost savings for cast iron (CI) pipes are not as dramatic, but still demonstrate a reduction to 60% of the repair costs for 150 mm diameter pipes and to 70% of the repair costs for 300 mm diameter pipes.