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The main purpose of a water distribution system (WDS) is to deliver safe water of desirable quality, quantity and continuity to consumers. However, in many cases, a WDS fails to fulfill its goal owing to structural and associated hydraulic failures and/or water quality failures. The impact of these failures can be reduced significantly if preventive actions are taken based on their potential of occurrences or if a failure occurs and is detected within a minimum period of time after its occurrence. The aim of this research was to develop a forensic system for WDS failures. As part of the proposed forensic analysis, a framework has been developed, which investigates structural and associated hydraulic failures as well as water quality failures and integrates all failure investigation under a single platform. Under this framework, four different models have been developed to evaluate and identify structural and associated hydraulic failures and water quality failures. If a failure is detected in the system, the framework is capable of identifying the most probable location of the failure. To investigate the effectiveness of the proposed framework, the developed models have been tested and implemented in different WDSs. [ABSTRACT FROM AUTHOR]

The goal of a water distribution system (WDS) is to deliver safe water with desirable quality, quantity and continuity to the consumers. In some cases, a WDS fails to deliver safe water due to the compromise/ failure of water quality which may have devastating consequences. The frequency and consequence of a water quality failure (WQF) can be reduced if prognostic analysis and necessary remedial measures are taken on time. This study developed a prognostic model to predict WQF potential in a WDS. The study identifies important factors (parameters) which can directly and/or indirectly linked to WQFs. These factors are classified into two groups-the causes of WQF such as lack of free residual chlorine, or excess of total organic carbon, and the symptoms of WQF such as taste & odor, color which are in fact the effects of certain causes of WQF. The interrelationships among the symptoms and the causes have been established based on extensive literature review and elicited expert opinion. A fuzzy-TOPSIS-OWA-based model has been developed to identify the impacts of different influencing parameters on the overall WQF potential. The developed model has been implemented for a WDS in Quebec City (Canada). To study the impacts of uncertainties of the influencing factors, a Monte Carlo simulation-based sensitivity analysis has been carried out. It is anticipated that the developed model can help water utilities to understand the role of different factors on WQF. [ABSTRACT FROM AUTHOR]

Designing a state-of-the-art online water quality monitoring system requires a comprehensive procedure for the selection of pertinent water quality parameters and available cost-effective and reliable sensors. Proper selection of pertinent contaminants/indicators for online monitoring ensures that the overall quality of the distributed water is not compromised and all regulations/guidelines are complied with fully. On the other hand, the selection of monitoring devices and sensors suitable for a typical online water quality monitoring system involves consideration of various factors including reliability, cost, response time, etc. In this paper, we illustrate the use of a multi-criteria decision analysis methodology based on an analytic hierarchy process to optimize the selection of indicator/contaminant sets and related water quality sensors as applied to drinking water distribution networks. A similar methodology could be used for most online monitoring applications in other areas. For the water distribution network application, we shortlisted 18 water quality indicators (WQI) from an initial list of 94 parameters. Similarly, from a comprehensive list of 71 potential water quality monitoring devices, nine were shortlisted for further analysis. Three of these nine monitoring devices were found to be suitable for monitoring 14 of the 18 shortlisted WQI. These three monitoring devices were found to be the best sensors because they demonstrated the ability to monitor 14 selected WQI simultaneously. [ABSTRACT FROM AUTHOR]

Heterotrophic plate count (HPC) is one of the most common indicators used to monitor microbiological water quality in distribution networks. This paper applies and compares two fuzzy rule-based models to estimate HPC levels in a distribution network using a limited number of water quality parameters. The proposed fuzzy rule-based models include Mamdani and TSK (Takagi, Sugeno, and Kang) algorithms. The models are discussed through a case study of a distribution network (DN) in Quebec City (Canada). Both models properly estimate when HPC levels (datum per datum) are low, however their predictive ability is limited when HPC levels are high. When the outputs (HPC levels) are converted into four classes and the models are used as 'classifiers', their performances are very good. The average percent deviation is lower for the TSK model (15%) than for Mamdani model (17%). Implemented as 'classifiers', both models can be used for identifying vulnerable locations for microbiological contamination within the DN. Given the complexity of the growth of HPC bacteria in water distribution networks and the involvement of numerous contributory factors; results obtained are 'promising'. Nevertheless, strategies to improve the models are also discussed. [ABSTRACT FROM AUTHOR]