The Water Services Corporation has, from its setting-up in 1992, been aware of the importance of achieving and sustaining an economically viable leakage level.
Quantification of leakages: The initial step taken by the Corporation was directed at quantifying leakage. Continuous data logging of all zone inlets and metering of all service connections allowed computations of leakage to be made on a ’bottom-up’ (using minimum night flows) basis and a ‘top-down’ (using annual water balance) basis, in accordance with recommended best practice from the International Water Association (IWA).
Management approach: Following initial leakage quantification based on sector night flows, the Corporation gradually implemented a leakage control programme based upon a delicate balance between five key components; pressure management, network rationalization, active leakage localization, dynamic leakage repair and replacement of critically weak pipework.
Initial programme in Gozo: As the implementation of a viable leakage control methodology in the whole of Malta would take a number of years, the Corporation initially targeted the smaller island of Gozo for comprehensive and integrated pilot leakage studies and trials. Over a six year period, a staged development took place. By 1999 Gozo annual system input volume had fallen to less than 70% of the 1995 figures and was actually lower than 1989 system input volume. Total leakage for the Island, calculated using the lowest night flow in each sector each week, was generally maintained at below 770 m3/day. This was less than a third of the initial leakage level calculated before on the same basis. Lessons learned in this first programme were then replicated in Malta. Corresponding to earlier leakage reductions in Gozo, in 1995 the first effects of falling leakage levels were felt in Malta also.
Standard methodology and indicators: Throughout 1998 and 1999 the Corporation participated in an international leakage comparison exercise, as part of the IWA ‘best practice’ Task Force activities. The comparison exercise carried out by the IWDC on 27 supply systems in 20 countries showed Gozo as one of the system leaders, with an ILI of close to 1.5, based on the initial calculations of leakage based on minimum night flows.
Ongoing developments: The ongoing major developments for both Gozo and Malta are, at present, as follows: A study into the quantification and control of apparent water losses, through the introduction of an Off-Site Meter Reading Scheme; the completion of an innovative economic leakage intervention model that is being developed; the development of an Integrated Water Management System, or IWMS which is, in essence, an information system that utilizes a corporate data model and a geographical information system (or GIS) to integrate the various functional modules within the Corporation’s sphere of operation.