In recent years water utilities are paying special attention to improve, throughout water audits, the volumetric efficiencies of their systems. Quantity and quality criteria performances are stressing this trend. To this regard, the enormous work done by the IWA during the last years is an evident signal of this international trend. Previously, the other leading organisation in the world, the AWWA had devoted lots of efforts to this same problem.
In this paper, taking into account all that previous work and accepting as general trend the importance of reliable metering a new and simplest audit is proposed. Clear preformance indicators as percentages annual volumetric values are well defined for being used for internal purposes instead of the technical ones recently defined by the IWA for benchmarking purposes.
Finally and based on the mathematical model or the network, as an alternative to continous night flow measurements, and on the complete database of the demand characteristics of the system, the paper presents a general procedure to evaluate the terms of the suggested balance. An example is presented for a further understanding of the proposed methodology.