Investigating apparent water losses in urban water distribution network: Application to a pilot study area in Antalya city

Many water authorities worldwide suffer from total water losses from urban water distribution networks. Total water losses are divided into two types of real water losses (RL) and apparent water losses (AL). The main reasons beyond AL are meter measurement inaccuracy and illegal water usage. Measurement inaccuracy depends on the age, size, type, installation of meters beside the water consumption profile. Total water losses are high in Türkiye in general while the related Turkish regulations ask all the water authorities to reduce total water losses up to 25% of the system input volume (SIV) on the long run. The purpose of this study is to assess the level of apparent water losses in a pilot study area in Antalya City. A hydraulically isolated area "District Metered Area (DMA)" was chosen from Konyaaltı district called as Molla Yusuf Neighborhood to apply this study. The DMA was equipped with monitoring system to measure the flow rates entering to the DMA. The monitoring system was connected to the ASAT SCADA system within an ongoing EU funded project. Six smart meters were installed to public areas such as schools and mosques in the DMA to detect post meter leakages that were common in the DMA. Besides the high level of leakages, the measurements conducted by the smart meters were used to analyze the suitability of meter sizes in the area which resulted that around one third of the investigated meters are with unsuitable sizes. Further investigation of the meter ages showed that a number of meters were with ages over 10 years which is above the age allowed by the Turkish regulations. Two hundred aged customer water meters were replaced with new ones in July 2024. The readings of the aged meters before replacement and the new meters after replacement for the same customers were compared. Comparison revealed an increase in the readings of the new meters during the first three months after their installation as the aged meters do not measure low flow consumptions. Investigations have shown that the customers in the DMA use local treatment units installed upstream of the meters where the backwashed water is not measured. All these reasons led to high AL of about 15% of SIV as given by the standard water balances (SWB) calculated for the DMA from October 2024 to April 2025 and that the AL exceeded the RL for the SWB in March-April 2025.