Impacts of water pressure on apparent losses due to accuracy of customer water meters

The sustainable management of water resources requires not only traditional approaches but also long-term planning that includes demand management. Water losses in urban water distribution systems present a significant challenge to achieving sustainable management goals. Water losses are classified into two main categories: real and apparent. Reall losses occur due to factors such as pipe cracks, tank overflows, pipe joints, and service connections, while apparent losses arise from issues like water meter errors and unauthorized water use. Apparent water losses result in substantial revenue losses for water utilities and municipalities. Reducing water losses will not only increase revenue but also improve service delivery in the long term. In well-managed water distribution systems, a large portion of apparent losses can be attributed to water meter measurement errors. These errors are influenced by factors such as metrological class, age, diameter, installation issues, and water pressure. Therefore, it is essential to assess water meter measurement errors under various flow and pressure conditions. This study aims to evaluate the impact of water pressure on water meter measurement errors. A total of 48 meters with different metrological and measurement mechanisms were tested at 9 flow rates (12, 25, 40, 120, 450, 900, 900, 1250, 2500, and 3125 L/h) and 5 water pressure levels (0.8, 1.5, 3, 4, and 6 bar). The meters tested include multi-jet (R100, R160, R200), volumetric (R200), and ultrasonic (R400) types. The results demonstrate that performance varies by meter type. Multi-jet meters exhibited high measurement errors at low flow rates, but these errors decreased as flow rates increased, remaining within acceptable limits. Volumetric meters generally had positive errors. Ultrasonic meters showed positive errors at low flow rates but overall performed better than other mechanical meters. These findings indicate that when selecting meters, water utilities should consider both consumption profiles and fluctuating water pressure conditions. The high measurement errors at low flow rates and the tendency of meters to exhibit positive or negative errors are critical factors for meter calibration and design. This study provides water utilities with key insights for optimal meter selection and reducing apparent losses, contributing to more effective water management strategies.