Analysis and assessment of water losses reduction effectiveness using examples of selected water distribution systems

The paper presents an analysis and assessment of water losses in the distribution systems of two water supply companies. The figures necessary to calculate water losses were obtained from the analyzed companies. They were used to determine: amounts of water losses in individual years, percentage water loss indices (WS), percentage index of network efficiency (D) as well as indices recommended by the International Water Association: real leakage balance, non-revenue water basic, unavoidable annual real losses, infrastructure leakage index, and also unit indices of losses per inhabitant (Q(los)), and network kilometer. Because of the relationship between the network failure intensity and water losses the failure intensity index was determined. The results of the carried out analysis allow to state that because of systematic actions in a complicated and extensive system of water distribution operated by company A in the years 2013-2018, the water losses maintained on a low level against a background of national figures as well as with respect to international standards. An average index of network failure intensity for distribution system A in the analyzed period was approximately 0.30 failure/(km y), in 2018, it was 0.25 failure/(km y) for the network, and 0.43 failure/(km y) for connections. For the distribution system of company B, situated in the area of underground mining impact, in the years 2013-2018 numerous loss indices were very dynamically reduced. An average failure intensity index for the entire water supply system went down from 2.4 failure/(km y) in 2013 to 0.44 failure/(km y) in 2018, which shows a low failure intensity for the system operating in the area of underground mining impact. The analysis and assessment of numerous water loss indices throughout the years proves the effectiveness of loss limitation strategies adopted by the analyzed companies. Within active loss management the analyzed waterworks for more than 10 y are implementing actions in the field of active leakage control, proper pressure management in water supply networks, speed, and quality of repairs, and also systematically carry out the pipe materials management. Because of the specific nature of water supply systems operation each company developed an own action program for losses reduction.