The fast logging method uses high resolution data to estimate the continuous flow boundary, i.e. the level at which flow is continuous, providing an estimate of leakage. This value is typically recorded at night when flow is at its lowest. When combined with the 15-minute night flow value (coarse flow) an estimate of night use can be made, which is further corrected for influences such as commercial properties or area size. The method also incorporates a seasonal model that predicts the increase in night use due to factors such as hot weather and holidays, and this allows the method to adapt to different seasons through the year and between years.
OFWATs PR19 guidance requires all water companies to move towards a consistent way of reporting leakage by the start of AMP7. Anglian Water currently calculate household night use (HHNU) from their individual household monitor (IHM), SODCON (Survey of domestic consumption). In order to improve the estimation of household night use, Anglian Water asked Artesia to help implement a new fast logging area monitor.
Artesia has since worked with Anglian Water to set up the fast logging monitor to the UKWIR best practice guidance including defining the correct sample size required, identifying suitable areas, developing the area specific calculations and implementing the process for reporting monthly household night use.
The monitor is statistically robust with a 90% confidence interval and representative of the company. This enables Anglian Water to report their night use robustly, and therefore report a more accurate leakage figure. It can also be developed to allow night use to be better predicted across Anglian Water’s DMAs, which will also improve leakage targeting and efficiency.