MWA Viewpoint on Water Loss Management at a National Level


Water losses are grouped into two types of loss; Real Losses, which are the physical leakages from a water distribution network, and Apparent Losses, which are caused by revenue meter under-registration, water theft and billing errors. Real Losses, or leakage, may be defined as a water resource. A utility’s Real Loss is viewed as an excellent indicator of the overall performance of the water utility, and is a versatile means of achieving an often-delicate balance between water supply and water demand. Reducing leakage will often defer major capital expenditure by reducing the need to build new water production plant. It will result in substantial savings for every cubic meter of water that is not lost, at a value of the marginal cost of water produced. It will significantly impact upon the environment through reduced energy consumption, resulting in less burning of fossil fuels. It will allow for better pressure management, leading to an enhanced level of service for the consumer. Finally, a well-managed leakage control initiative will result in less futile excavations for suspected leakages and less disruptions in the repair of existing leakages.

Whilst Real Losses are an expense due to lost water, Apparent losses are not so much an expense to the water utility as they are a loss of potential revenue. Apparent Losses relate to water that is being consumed, but not being paid for. Thus for every cubic metre of water unbilled as a result of an Apparent Loss, the water utility loses the opportunity of collecting money for that cubic metre of water, and transfers that cost to someone else. Water loss management of the national distribution system is primarily the responsibility of the Water Services Corporation, as the water service provider, and the Malta Resources Authority, as the national regulator. Other primary stakeholders exist, such as the Ministry of Finance, the Economy and Investment, responsible for establishing national policy for resource investment and utilization.

Theme 1: Methodology

The national service provider must implement adequate, and internationally recognized, water loss control methodologies for both Real Losses and Apparent Losses. The predominant international organizations in this regard are the International Water Association (IWA) and the American Water Works Association (AWWA). It is to be expected that the national service provider affiliates with these organizations, and acquires regular updates on; a) best practice, b) performance indicators, and c) benchmarks that are being applied towards water loss management.

The MWA recommends that IWA-established water loss methodologies be applied, these being similar to the AWWA methodologies and well established internationally. The IWA-established methodology for Real Loss control consists of 4 components that must be applied in conjunction to effectively control water leakage. These are; active leakage control, active + passive leakage repair, pressure management, and network design/rehabilitation/replacement. A failure to effectively control any one of these components will inevitably result in rising leakage levels. The IWA-established methodology for Apparent Loss control also consists of 4 components that must be collectively applied. These are; revenue water meter management, water theft control, meter consumption measurement, and control of billing anomalies. Again, a weakness in any one of these four dimensions will result in unbilled water usage, at the expense of third parties.

Theme 2: Measurement

The methodologies that have been described cannot be applied correctly without a comprehensive measurement strategy at various organizational levels. Inadequate measurement will result in miscalculated Real and Apparent Loss values, and the misdirection of loss control efforts and resources. At a national and master zone/regional level, water balance measurements should be taken by the utility at a minimum of once every three months, ideally monthly or even more frequently. The internationally established water balance format is graphically illustrated below:

Figure 1: The Water Balance

Metering and data logging of all distribution zones must be taken weekly, with pressure and flow monitoring on all zone inlets, and pressure monitoring on all critical nodes. Problems often occur when the water utility may fail to monitor pressures at critical nodes, resulting in network pressures falling below the established level of service (set at 1.5 bar in most localities) and consequentially false leakage calculations. Electronic data management of the quantities of data captured is essential, as is an effective data management strategy. Measurement and monitoring of the network needs to be extended into a centralized geographical information system (GIS), that is dynamically managed and accessible by all water loss management personnel. Attributes to be captured include leakage repair information, network infrastructure information, consumer geocoded data, and many more attributes. This GIS function must be owned and managed by the water utility, as it is one of the organization’s core competencies. SCADA should be used to assist in the monitoring and control of the national distribution network. Measurement extends to calculations of performance indicators and benchmarks. The MWA recommends that the Infrastructure Leakage Index (ILI) Overflow or leakage of storage tanks Transmission and distribution mains Service connections to meter Non Revenue Water or (unbilled volumes) Unbilled metered consumption Unbilled unmetered consumption Metering inaccuracies Unauthorized consumption Billed metered consumption (including water exported) Revenue Water (or billed Billed unmetered consumption volumes) System Input Volume Autorized consumption Billed authorized consumption Unbilled authorized consumption Apparent losses Water losses Real losses and an Apparent Loss Indicator (ALI) are used, in conjunction with the above water balance, to measure the utility’s effectiveness in controlling water losses. Other PI’s can support the use of the ILI, measuring employee motivation, leak targeting success, training provided, employee turnover, and such. The MWA recommends that the water utility applies established PI’s from a range published by the IWA.

Theme 3: Control

Control of the water utility’s loss management strategy must come from within as well as from external sources. The main internal challenge is in sustaining a strong corporate culture towards loss control, a culture that has been well established over the years and is easily destroyed. One has but to see the excellent efforts implemented by the ATIGA Consortium in Malta (UNDP 1972), that were subsequently wiped out due to a lack of management vision in subsequent years. Building culture should be supported by training and motivating loss control staff, particularly because their task is highly tacit and often unappreciated. Control must be extended towards the monitoring of the effectiveness of equipment, instrumentation, methodologies and established procedures.

Externally, control of the water utility’s loss efforts should be regularly carried out by the local regulator, the MRA. This must be more than a cosmetic effort, and must look carefully into the implementation of all of the components of the Real and Apparent Loss methodologies. The regulator must also carefully and diligently analyze the mechanisms being applied by the utility to measure the various loss parameters, and the reliability and validity of the data being acquired. Questions that should be asked include; are DMA’s being tested regularly to ensure hydraulic encapsulation? Are all critical nodes being continuously pressure logged? Is the GIS effectively capturing all ensuing network information? Are ILI calculations being properly carried out?

Theme 4: Economic Perspective

The water utility must ensure that proper economic calculations are being carried out when setting targets for both Real and Apparent Loss control. Economic target setting should have both a short-range and a long-range perspective. For the short range, economic leakage intervention modeling is advocated, this for each DMA and for a weekly time frame. For the long-range an economic model must be calculated at least annually, computing the minimum economic level of leakage. This must pull in a wide range of variables into the calculation, such as the cost of not sustaining leakage resources, the deferred cost of capital, and the value of consumer dissatisfaction.