Calculation Proposal for the Economic Level of Apparent Losses (ELAL) in a Water Supply System

The manuscript describes a simplified methodology with which to assess the economic level of apparent losses (ELAL) in a water utility. This economic point corresponds to the break-even point for which the marginal benefit of increasing the frequency of the apparent losses’ reduction activities equalizes the marginal cost of their implementation. For this calculation, each apparent loss component, as defined by the International Water Association, has been subdivided into two additional categories. These categories have been established depending on how periodic activities conducted by the water utility to reduce apparent losses—namely water meter replacement and customers’ connection inspections—may affect their magnitude. It has been found that the ELAL is influenced by intervention costs, the degradation rate of the accuracy of water meters and water tariffs. In addition, this work defines a set of performance indicators to benchmark the apparent loss’s performance relative to the minimum achievable and optimum levels of the losses. Finally, two case studies on how the proposed calculation should be applied have been added to the appendices.