Examining the energy performance associated with typical pipe unit head loss thresholds

The energy performance of water mains is rarely used as a criterion for pipe rehabilitation decisions, yet there is a need to identify the worst‐performing pipes to target investment wisely. This study links pipe characteristics with energy performance to understand how traditional pipe replacement thresholds perform in terms of energy. A cross‐correlation analysis between pipe characteristics and pipe energy performance metrics, using a benchmarking data set of more than 20,000 water mains from 17 distribution systems, showed that unit head loss is closely related to net energy efficiency and the energy lost to friction (ELTF) in pipes, along with flow. Under average flow conditions, 3.2% of the pipes exceeded 3 m/km (ft/1,000 ft) of unit head loss, with 1.1% exceeding the more stringent 10 m/km threshold. Over 90% of pipes have a unit head loss below 1 m/km, which corresponds to an ELTF of 1.9%.