Pipe Efficiency Analysis at a Water Utility

A water utility company has many actions and decisions to take in order to run operations efficiently and effectively. One of them is to decide which types of pipe(s) to install as they do not all perform the same. Because these pipes may remain installed underground for more than 100 years, the decision to install is substantially binding. The pipe types considered here are ductile iron (DI), cast iron, PVC, and concrete cylinder (CC). The approach was to study cost and quality control measures and then apply data envelopment analysis in linear programming to determine the relative inefficiency of the specific pipe type in comparison to the rest of the pipe system. Data were taken from the main-break database and records and reports published by the Honolulu Board of Water Supply. Quality control measures evaluated included availability and reliability at the system and individual levels. It was determined that CC pipes were more inefficient than the others. Multiple scenarios of output measures were evaluated, such as combinations of system and individual levels, availability, and reliability. In all such evaluations, it was conclusively seen that CC pipes were relatively inefficient. Consequently, it is recommended the utility plan to replace CC pipes with corresponding DI and PVC piping.