Assessing the results of a virtual pressure management project applied in Kos Town water distribution network

Water pressure management (PM) is one of the most cost-effective ways for a water utility to reduce water leakage, pipes’ bursts, improve the level of services provided to its customers and lower its operating expenses. The present paper presents a pilot pressure management project designed for the water distribution system of Kos Town (capital of Kos Island, Greece). Kos Town experiences extreme variations regarding its population served by the local water utility between summer and winter. The PM implementation was achieved by developing the system’s hydraulic simulation model using the commercial software, Watergems V8i. For the water demand allocation of the model, the spatial allocation of water demand at street level approach was used because the customers’ water meters were not geo-referenced. The results were compared to multiplicatively weighted Voronoi diagram method’s results and to field measurements. The simulation process took into account the respective demand patterns of the various types of urban water uses, considering the water volume being lost through leaks/breaks occurring in the pipe network, as a competitive use. Each kind of water used was divided into a pressure dependent part and a volume depended one. Both parts were introduced to the model. The designing phase of the PM included the formation of district metered areas and Pressure Reducing Valves (PRVs) installation. The reduction in pressure within acceptable regulation limits resulted in the reduced needs of System Input Volume (SIV), due to significant reduction of anticipated water losses and authorized consumption, as both these “water uses” are pressure dependent. There were many simulations of different scenarios in time (monthly) and PRVs’ configuration. Regarding the latter, several types of PRVs and their settings were tested (e.g. fixed PRVs; PRVs with modified daily pattern; PRVs combined with local pressure boosters). The virtual scenarios resulted in reducing the SIV up to 24%. The related water savings have a direct positive environmental impact on the aquifer supplying Kos Town. These outcomes persuaded the local water utility to proceed with the actual implementation of the pilot study by installing the necessary system devices (either for measuring data or for pressure reducing) in more than 40 manholes across the town. © 2015 Balaban Desalination Publications. All rights reserved

Assessing the results of a virtual pressure management project applied in Kos Town water distribution network

Water pressure management (PM) is one of the most cost-effective ways for a water utility to reduce water leakage, pipes’ bursts, improve the level of services provided to its customers and lower its operating expenses. The present paper presents a pilot pressure management project designed for the water distribution system of Kos Town (capital of Kos Island, Greece). Kos Town experiences extreme variations regarding its population served by the local water utility between summer and winter. The PM implementation was achieved by developing the system’s hydraulic simulation model using the commercial software, Watergems V8i. For the water demand allocation of the model, the spatial allocation of water demand at street level approach was used because the customers’ water meters were not geo-referenced. The results were compared to multiplicatively weighted Voronoi diagram method’s results and to field measurements. The simulation process took into account the respective demand patterns of the various types of urban water uses, considering the water volume being lost through leaks/breaks occurring in the pipe network, as a competitive use. Each kind of water used was divided into a pressure dependent part and a volume depended one. Both parts were introduced to the model. The designing phase of the PM included the formation of district metered areas and Pressure Reducing Valves (PRVs) installation. The reduction in pressure within acceptable regulation limits resulted in the reduced needs of System Input Volume (SIV), due to significant reduction of anticipated water losses and authorized consumption, as both these “water uses” are pressure dependent. There were many simulations of different scenarios in time (monthly) and PRVs’ configuration. Regarding the latter, several types of PRVs and their settings were tested (e.g. fixed PRVs; PRVs with modified daily pattern; PRVs combined with local pressure boosters). The virtual scenarios resulted in reducing the SIV up to 24%. The related water savings have a direct positive environmental impact on the aquifer supplying Kos Town. These outcomes persuaded the local water utility to proceed with the actual implementation of the pilot study by installing the necessary system devices (either for measuring data or for pressure reducing) in more than 40 manholes across the town. © 2015 Balaban Desalination Publications. All rights reserved

Non-revenue water reduction through pressure management in Kozani’s water distribution network: from theory to practice

During the last few years, many water utilities are facing difficulties with the high non-revenue water (NRW) levels. Among the NRW management strategies, water pressure management (PM) is the most popular towards the goals of effective and efficient water use. In an effort to improve the level of services provided to consumers, minimize its operating expenses and reduce water leakage and pipes’ bursts, water utilities rely on water PM although it is one of the most expensive methods. This study analyses a methodology of calculating economic benefits and revenue losses caused due to the reduction of a system’s operating pressure. The reduction of System Input Volume causes direct benefits (e.g. reduced energy costs), while the reduced burst frequency causes direct (e.g. maintenance cost reduction) and indirect potential benefits (e.g. reduction in personnel, insurance and vehicle operation costs). The revenue losses are caused mainly due to the reduction of pressure-dependent water consumption. In the case of Kozani city in Greece, the economic impact of dividing its water network in District Metered Areas and applying 5 PM interventions based on installing Pressure Reducing Valves is calculated, using the system’s hydraulic model. © 2015 Balaban Desalination Publications. All rights reserved

Reaching economic leakage level through pressure management

High non-revenue water (NRW) values as a percentage of system input volume form a serious problem that many water utilities worldwide have to confront nowadays. There are ways to mitigate the effect by adopting strategies with short- and long-term results. Water pressure management (PM) is one of the most efficient and effective NRW reduction strategies. To calculate pressure management of economic level of leakage (ELL), several steps have to be taken, such as full water costing, calculation of economic benefits and losses of PM interventions and definition of the related investment's break-even point. In this paper, the results of these three procedures required to define the ELL level are analyzed, in order to present the way they are linked together. The water distribution system of Kozani city (in Northern Greece) is used as the case study network. The results of both the net present values PM implementation results and the investment's break-even estimation are analyzed. © IWA Publishing 2016

Properly allocating the urban water meter readings to the nodes of a water pipe network simulation model

This paper presents an alternative approach regarding the spatial allocation of the actual water demand when developing the hydraulic simulation model of an urban water pipe network. This approach can be applied in cases where the customers' water meters are not georeferenced (usually the case in developing countries), reducing the computational time needed for the model's calibration increasing, thus the method's cost effectiveness. The simulation process takes into account the respective demand patterns of the various types of urban water uses, considering the water volume being lost through leaks/breaks occurring in the pipe network, as a competitive use. Each kind of water use is divided in its pressure-dependent part and its volume depended one. Both parts are introduced to the model. The water losses' diurnal pattern calculation method is also thoroughly presented. Kos Town (Greece) water pipe network is used to demonstrate the entire process. To prove its effectiveness, the results of the new proposed method were compared to Voronoi diagrams method's results and to field measurements

The joint effect of water price changes and pressure management, at the economic annual real losses level, on the system input volume of a water distribution system

This study attempts to examine the factors affecting the residential water demand level in the city of Kozani in Greece. Based on an 8-year (2005-12) detailed sample of residential water demand panel data, the values of the water price (WP) elasticity of residential demand are identified, and the influence of socio-economic and demographic factors and climate conditions on water-use levels and trends are analyzed. The system's response in terms of system input volume is examined (through the simulation model developed for the network and a pressure management (PM) application) for different scenarios of increased and decreased WP levels. Various scenarios for the real losses were examined, starting from their current level (current annual real losses), down to their economic level (economic annual real losses) after implementing PM measures. The overall objective is to determine and record the overall reaction of consumers to the changing WPs as a result of the full water cost principle implemented. © 2015 IWA Publishing

Developing a methodology towards full water cost recovery in urban water pipe networks, based on the "user-pays" principle

In the present paper, using an urban water supply and distribution system as a case study (city of Kozani, Greece), the components of the full water cost (direct-DC; environmental-EC; resource-RC) are analysed, introducing approaches for their reliable calculation. Regarding the DC, the marginal capacity cost and the necessary preconditions for its integration to the final water price are analyzed. Regarding EC, the role of non urban water users in creating EC is presented. Regarding RC, water losses are introduced as a competitive use. The role of "next more expensive solution" approach in defining ways for costs proper calculation is analyzed. © 2013 The authors

Pressure Management and Energy Recovery Capabilities Using PATs

Hydro-turbines are widely used in small water energy production plants in order to turn water kinetic energy to electricity. PATs (Pumps working As Turbines) are micro-turbines (small sized compared to the usual ones) working on reverse mode compared to the usual pumps. Installation of a PAT aims to produce energy along with managing/keeping the downstream pressure to a desired level. PRVs (Pressure Reducing Valves) are used to decrease pressure aiming to reduce water losses linked to this extra pressure potential available. The current study focuses on the possibility to replace a PRV with a PAT in a real water distribution network checking its ability to reduce pressure to acceptable levels as well as produce significant amount of energy. The water distribution system of Kozani city (in Northern Greece) is used as the case study network. Various operating scenarios regarding the exact location of the PAT were checked in the network's calibrated hydraulic model with interesting results. © 2016 The Authors

Combining pressure management and energy recovery benefits in a water distribution system installing PATs

Gravity can play a beneficial role in certain water distribution networks (WDNs), although sometimes high nodal pressures occur. Excessive pressure may lead to several negative effects regarding the network's operation and life. Thus water utilities are obliged to implement pressure management (PM) policies. Instead of just 'destroying' energy using conventional measures, there are other PM options, like installing pumps working as turbines (PATs) that can recover energy at the same time. Hydro-turbines are widely used in small water energy production plants that produce electricity utilizing the water's kinetic energy. PATs are micro-turbines (compared to the usual ones) used in reverse mode to ordinary pumps. Installing a PAT aims to not only produce energy but also keep the pressure of the downstream pipe to a desired level. Pressure reducing valves (PRVs) are able to decrease pressure too, thus reduce also water losses. This study attempts to exploit every possibility of replacing a PRV with a PAT and check a PAT's ability to reduce pressure to acceptable levels as well as produce a significant amount of energy. Kozani's (Greece) WDN is used as the case study. Various scenarios were checked, utilizing the network's calibrated hydraulic model with intriguing results. © IWA Publishing 2017

Forming District Metered Areas in a Water Distribution Network Using Genetic Algorithms

Dividing a water distribution network into District Metered Areas (DMAs) is the first vital step towards water loss management. It is a multivariate problem. Techniques based on Genetic Algorithms is a proven way to provide a very good solution to optimization problems. Basic requirement is that each problem must be well described by an objective function. The formation of the objective function is tested through Matlab's optimization tools. The results of the genetic algorithm are compared to the results of an algorithm (in C++ Language) developed in an earlier stage to provide optimal system pressure reduction by closing indicated pipes. The process for the formation of the objective function and a case study on a real network are presented