Characterization of night-time water consumption of non-residential users belonging to the service industry

Night-time water consumption (NWC) - typically used in the Minimum Night Flow (MNF) method for leakage assessment in water distribution networks (WDNs) - is a key but still poorly investigated parameter, especially in relation to the non-residential sector. This study analyses hourly smart-meter data from 44 small-scale service-industry (SI) users located in Northern Italy, each monitored over a one-year period across distinct monitoring campaigns conducted between January 2017 and January 2026. The dataset includes six user categories: shops, offices, catering services, wellness activities, recreational activities, and police stations. A multi-phase methodology is applied to address: (i) NWC characterization across SI categories; (ii) NWC seasonal variability; and (iii) NWC relationship with yearly billed consumption. Overall, results show low average values of NWC (average 2.8 L/user/h), lower than benchmark value of 7.4 L/user/h reported in the technical literature for the non-residential sector. Strong heterogeneity is observed across categories, with shops and offices exhibiting negligible consumption, whereas catering services show higher and more variable NWC. Seasonal effects are also observed, with higher NWC in warmer months for most users. A statistically significant correlation is found between yearly billed consumption and NWC, indicating the possibility of predicting NWC based only on billing data in the absence of category information. By providing insights into category-specific NWC and individual user's behaviours, the findings can support an improved MNF-based leakage assessment.