Pipe leak measurement and assessment

A method of estimating characteristics of new leaks that have formed in an isolated section of a water distribution system that is supplied through a pressure reducing valve, the method comprising:

• (i) determination or estimation of leak characteristics of a leak or leaks present in the isolated section of the water distribution system during a period of minimum night flow of a first, earlier date by performing the following steps:
• (i.i) using the pressure reducing valve to vary the pressure in the isolated section of the system to at least two different pressure settings during the minimum night flow period of the first date;
• (i.ii) measuring, during said period of the first date, pressure and flow rate into the system at each pressure setting;
• (i.iii) estimating leakage rates for the first date by subtracting an estimated user consumption during said period of the first date from the measured flow rates of said period of the first date;
• (i.iv) estimating the leak characteristics of the first date from the pressure measurement readings of step (i.ii) and the leakage rate estimates of step (i.iii);
• (ii) determination or estimation of leak characteristics of a leak or leaks present in the isolated section of the water distribution system during a period of minimum night flow of a second date which is later than the first date, by performing the following steps:
• (ii.i) using the pressure reducing valve to vary the pressure in the isolated section of the system to at least two different pressure settings during the period of minimum night flow of the second date;
• (ii.ii) measuring, during said period of the second date, pressure and flow rate into the system at each pressure setting;
• (ii.iii) estimating leakage rates for the second date by subtracting an estimated user consumption during said period of the second date from the measured flow rates of said period of the second date;
• (ii.iv) estimating the leak characteristics of the second date from the pressure measurement readings of step (ii.ii) and the leakage rate estimates of step (ii.iii);
• and
• (iii) comparing the estimated leak characteristics derived for the second date with those derived for the first date to establish a difference in the estimated leak characteristics, thereby to determine that on the second date there is a new leak or new leaks in the isolated section of the system, wherein a new leak or new leaks refer to a leak or leaks present in the isolated section of the water distribution system on the second date but not on the first date.