Given the commonly estimated ~20% leakage loss rate in municipal water main systems (the oldest urban infrastructures), the issue of water losses in the "last mile" delivery systems is just as important as the problem of finding "new water" to put into such systems.  After all, A WATER SHORTAGE IS BY DEFINITION THE DIFFERENCE BETWEEN AVAILABLE WATER AND ACTUALLY DELIVERED WATER.  Unfortunately, water measurement systems have been historically under PUC regulation, whereby water losses simply go into the rate base.  In the military/aerospace industries, great emphasis is placed on the accurate measurement of critical flows, e.g. turbine engines for entire fleets of aircraft are selected based on specific fuel consumption advantages as small as 0.1%, accurate launch refueling of two-phase cryogens, etc..  Measurement uncertainty of sensors has highest priority, and calibration of sensors is performed at 12 month intervals. An noteable extreme deficit among water utilities is their virtually non-existent calibration of distribution sized water main meters with low uncertainty.  Note however, that calibration of sensing systems is a metrologically legal requirement of all quality management systems, e.g. ISO 9000, ANSI/ASME NQA-1, MIL-I-45208, etc.  Thus, water utility companies really do not have a rigorous quality management systems -- which is reflected by ongoing large leakage losses. Until water distribution organizations begin to routinely calibrate their larger water main system flow sensors, e.g. up to 24", accurate water audits, leakage losses, etc., will generally continue to be estimates at best.  Early detection of smaller leaks (detected cumulatively) will continue sometimes for years / decades before being reported by ordinary citizens as potholes, etc. Detection, location, and prioritization of the multitude of water main leaks will be an ongoing decade long process.  We should start with the basics: better calibration of large flow measurement systems.

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Given the commonly estimated ~20% leakage loss rate in municipal water main systems (the oldest urban infrastructures), the issue of water losses in the "last mile" delivery systems is just as important as the problem of finding "new water" to put into such systems.  After all, A WATER SHORTAGE IS BY DEFINITION THE DIFFERENCE BETWEEN AVAILABLE WATER AND ACTUALLY DELIVERED WATER.  Unfortunately, water measurement systems have been historically under PUC regulation, whereby water losses simply go into the rate base. 

In the military/aerospace industries, great emphasis is placed on the accurate measurement of critical flows, e.g. turbine engines for entire fleets of aircraft are selected based on specific fuel consumption advantages as small as 0.1%, accurate launch refueling of two-phase cryogens, etc..  Measurement uncertainty of sensors has highest priority, and calibration of sensors is performed at 12 month intervals.

An noteable extreme deficit among water utilities is their virtually non-existent calibration of distribution sized water main meters with low uncertainty.  Note however, that calibration of sensing systems is a metrologically legal requirement of all quality management systems, e.g. ISO 9000, ANSI/ASME NQA-1, MIL-I-45208, etc.  Thus, water utility companies really do not have a rigorous quality management systems -- which is reflected by ongoing large leakage losses.

Until water distribution organizations begin to routinely calibrate their larger water main system flow sensors, e.g. up to 24", accurate water audits, leakage losses, etc., will generally continue to be estimates at best.  Early detection of smaller leaks (detected cumulatively) will continue sometimes for years / decades before being reported by ordinary citizens as potholes, etc.

Detection, location, and prioritization of the multitude of water main leaks will be an ongoing decade long process.  We should start with the basics: better calibration of large flow measurement systems.