Evaluation of statistical sampling for the assessment of residential consumption totals in water distribution networks

Abstract

The paper provides insights into stratified sampling, a standard statistical technique that may be employed to assess domestic water use in water distribution networks. The basic idea is to use only few meters to provide inference on the total water consumption of a network or of a district metered area through the knowledge of some additional stratification variables such as household typology, size and occupants number. Since any sampling procedure assumes that the variance of the variable at stake is known, either a suitable amount of past consumption data is necessary, or a specific preliminary survey must be carried out, in order to define the sampling plan. An application with real consumption data from a small municipality in Sicily (Italy) shows that number of occupants for each household is sufficient to design an effective sampling plan and that the methodology can be successfully applied in the technical practice, thus allowing to dramatically reduce the number of customer meters to be read in order to quantify total water consumption compared to standard practice based on the reading of all meters.