Water supply and distribution infrastructures are vital for current life. They have a significant role in public health, providing safe water for drinking and human consumption as well as for essential non-potable uses such as fire fighting. These diverse objectives create challenges for everyone who must address in some way the actual performance of the system. This research critically evaluates all common objectives of conventional design approaches and evaluates the advantages and drawbacks of various performance measures. New ideas for a more realistic and comprehensive approach to the design, operation assessment of WDS are proposed. A new approach, called a Risk-based Performance Assessment, for hydraulic performance evaluation is tentatively proposed. It is based on integration of reliability, resiliency, and vulnerability as three basic operational indices in the operation of WDS. Furthermore, the Total Life-cycle Cost evaluation approach is tentatively proposed based on considering all major costs of a WDS.

This thesis compares the Roman water systems in Pompeii and Nîmes in order to understand the relationship of the water systems to the urban layout of the city. Analyzing the nature and location of an urban water system enables a better understanding of the urban functions within a city, as well as prediction of the nature and location of particular structures within an urban plan. I examine the primary sources of Vitruvius and Frontinus, the topography of each city, the urban orientations, the hydro-technologies employed, and the public and private buildings to which water would have been supplied. My survey of water systems begins with the source of water and the aqueduct that supplies each city and also assesses the relationship of the aqueduct to the rural landscape. In both Pompeii and Nîmes, water from the aqueduct is deposited in a central settling tank within the city and dispersed from the settling tank to various destinations. I have analyzed the buildings, public and private, that had or would have required direct access to this water source and created water supply routes for each colony.

Hierdie verhandeling handel oor Nie-verrekenbare water (NVW) van pypnetwerkstelsels, oorsake wat daartoe lei sowel as die verskillende faktore wat daarby betrokke is. Verskillende wyse waarop die NVW van 'n netwerk bepaal kan word, word ondersoek en metodes vir die vermindering van NVW word bespreek. NVW van pypnetwerkstelsels bestaan uit vier komponente. Sekere van hierdie komponente is van groter belang, veral werklike verliese, as ander. Die volgende vier komponente kan onderskei word: <ul> <li>werklike verliese as gevolg van lekkasies wat ekonomies herstelbaar is</li> <li>onvermydelike verliese as gevolg van klein lekkasies wat nie ekonomies herstelbaar is nie</li> <li>oënskynlike verliese as gevolg van stadige perseelmeters aan die leweringskant</li> ongemeterde aftrekkings deur brandkrane en spoelkleppe.</li></ul> Watermeters en hulle akkuraatheid het 'n baie definitiewe invloed op die NVW van 'n netwerk. So byvoorbeeld kan daar 'n aansienlike toename in die NVW voorkom indien meters nie die korrekte volumes wat deur hulle vloei, registreer nie. Pypmateriale en konstruksiemetodes het 'n invloed op NVW en is ondersoek. Indien lae kwaliteit materiaal gebruik word en verkeerde installasie metodes gebruik word lei dit tot meer lekkasies en 'n hoë NVW. Lekkasies in 'n netwerk het 'n invloed op die NVW. As gevolg hiervan is verskeie metodes van lekkasie opsporing ontwikkel. Hierdie verskillende metodes van lekkasie opsporing is in die veld ondersoek om sodoende die bruikbaarheid en geskiktheid van elk te evalueer. Resultate van hierdie ondersoeke dui daarop dat 'n kombinasie van metodes die mees geskik voorkom vir lekkasie opsporing en waterverliesbeheer. Hierdie metodes bestaan hoofsaaklik uit visuele naspeur, soniese sporing sowel as verliesvloeimeters. ENGLISH : The Subject of this thesis is Unaccounted for Water (UAW) of Water distribution Networks. Various causes and factors are responsible for the UAW of networks. These have been studied together with various methods of control. Four components make up the UAW of networks with some being of bigger importance, especially actual losses, than others components are: <ul> <li>actual losses due to leaks which are economically repairable</li> <li>unavoidable losses due to small leaks which are not economically repairable</li> <li>apparent losses due to underregistering stand meters</li> <li>unmetered draw-offs via hydrants and flushing valves.</li></ul> Water meters are used to determine the UAW of a closed network by means of measurements on both sides of the network. Inaccurate slow meters can be the cause of the UAW being much larger than otherwise. Pipe materials and construction methods have been studied in as far as it concerns the UAW. Low quality materials and bad construction methods lead to increases in the UAW. Leaks in a network have an influence on the UAW and therefore various methods of leak detection have been developed. Field investigations concerning these various leak detection methods were carried out and these methods were evaluated. From results of these field investigations it became clear that a combination of methods was most suitable for leak detection and water loss control. These methods include the visual method as well as sounding devices and waste detection meters. / Dissertation (MSc)--University of Pretoria, 1978. / Chemical Engineering / unrestricted

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The water distribution system design problem consists of finding a minimum cost combination of network layout and sizes of system components so as to satisfy flow demands, minimum and maximum head requirements and a reliability criterion. A two step procedure is proposed to find a near optimal design. The first step considers obtaining a near optimal tree layout using a heuristic tree search algorithm. Two different methods are followed for the tree search - one for single source networks and the other for multiple source networks. The second step adds loop forming redundant links to the tree layout in such a way that every demand node has two paths from source node(s). The methodology is applied to a single source network and a multiple source network. In both the cases better results arc achieved than those obtained previously by other researchers. / Master of Science

Customer complaints of red water problems remain to be a frequent occurrence for water utilities. While material sources may vary, it is generally accepted that iron rust resulting from corrosion of iron based pipes is the predominant cause of red water issues. Recent efforts have lead to the development of a number of models that predict the occurrence of iron release and subsequent red water formation. This paper provides a detailed analysis of recently developed iron corrosion release models. Significant disagreement exists as to the processes and mechanisms leading to the release of iron corrosion materials into the water supply. This lack of consensus is made evident when comparing each of the iron release models. Considerable variation exists as to mechanisms considered and specific modeling goals. While each model may be beneficial for simulating certain aspects of corrosion release, no single model has been developed that provides a comprehensive portrayal of iron corrosion release phenomena. / Master of Science

Potable water distribution systems are broken into major and minor distribution networks. Major water distribution networks refer to large-scale municipal pipe systems extending from the treatment plant to the upstream node of the water service line for buildings. Minor water distribution systems, also referred to as plumbing water distribution systems, run from the upstream node of the water service line to all interior plumbing fixtures and demand nodes associated with the building. Most texts and research papers focus on major systems, while only a small number of documents are available concerning the design and analysis of minor systems. In general, the available minor system documents are quite prescriptive in nature. This thesis presents a comprehensive evaluation of contemporary plumbing water distribution system design. All underlying theory is explained and advantages and drawbacks are discussed. Furthermore, contemporary methods for designing minor distribution systems have come under recent scrutiny. Issues have been raised regarding the accuracy of water demand estimation procedures for plumbing systems, namely, Hunter's method. Demand estimates are crucial for designing minor piping systems. The formulation and application of a pressure-driven design approach to replace Hunter-based design methods is presented. EPANET, a commonly used hydraulic modeling software package, is utilized to evaluate network behavior. Example applications are presented to illustrate the robustness of a pressure-driven approach, while also allowing the evaluation of plumbing water distribution system performance under worst-case loading conditions. / Master of Science

Water distribution modeling for hydraulics and water quality is an important tool for managing system performance of water utilities. An important component of a water distribution model is the calibration of a network model with field data in the real world system. The calibration effort requires a protocol or selection criteria for the location of field measurements that best support the calibration effort. A water distribution model was constructed at the University of Kentucky hydraulics lab for the purpose of investigating the performance of water distribution models. The lab model contains numerous hydraulic (pressure, flows) and water quality (concentrations) sensors for measuring system characteristics. This research work utilizes the lab model to compare hydraulic calibration using pressure heads from hydraulic data, velocities from water quality data, and combinations of both as the basis of calibration. It also presents an example of a small experimental system where velocity data as a basis for a calibration effort and pressure based data as a basis doesn’t converge to the same solution. The results of the research demonstrate the necessity of using both velocity & pressure data for hydraulic calibration to avoid compensating errors.

ABSTRACT DESIGN OF WATER DISTRIBUTION SYSTEM BY OPTIMIZATION USING RELIABILITY CONSIDERATIONS Akdogan, Tevfik Department of Civil Engineering Supervisor : Assoc. Prof. Dr. Nuri Merzi April 2005, 91 pages In spite of a wide research, design of water distribution networks are not realized using optimization techniques. One reason for this fact is, design of water distribution networks is evaluated, mostly, as a least-cost optimization problem where pipe diameters being the only decision variables. The other motivation for preferring the traditional modeling practice is that, existing optimization algorithms are not presented to the user as friendly as it should be. In fact, water distribution systems are very complex systems such that it is not easy to obtain least-cost design systems considering other constraints such as reliability, in addition to classical constraints related to hydraulic feasibility, satisfaction of nodal demands and requirement of nodal pressures. This study presents a user-friendly package concerning the design of water distribution networks by optimization using reliability considerations / this works employs the algorithm proposed by Goulter and Coals (1986). At the end, a skeletonized network design is offered / various costs are estimated in regard to the degree of reliability.

Nitrification in water distribution networks has become a growing concern for water supplies in the United States. The use of chloramines as a disinfectant in distribution pipe networks has become increasingly popular to reduce the disinfectant byproducts that are formed with free chlorine. In chloraminated systems there is potential for nitrification to occur because it reduces chloramine residuals. As chloramines decompose in the network, ammonia is released. Nitrifiers oxidize ammonia into nitrites, which react with chloramines resulting in its further reduction. As this cycle continues, chloramines will be consumed faster in the network, causing regrowth of heterotrophic bacteria. A study was conducted to compare the Fargo and Moorhead distribution networks for the occurrence of nitrification and their potential to deteriorate water quality. Each distribution network was analyzed independently for variations in operational conditions and water quality parameters that can serve as indications of nitrification in a distribution network. / Moorhead Water Treatment Plant