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The paper assumes that the measure of the loss of safety in water distribution is the risk related to the occurrence of some undesired events such as the failure to meet certain (required) water quality conditions (that may have negative impacts on the consumer health), or a severe disruption of the water supply services. In this aspect, risk is assessed using the expected value of losses (hazardous effects) that may occur as a result of the occurrence of the undesirable events. A comparison of the determined values with the risk acceptability criteria is the basis for the safety assessment. The analysis was made based on the available operational data of the water supply subsystem. The analysis covered the period from 2011 to the third quarter of 2021 and was prepared on the basis of available physicochemical and microbiological analyses of water performed at the water and microbiology laboratory of the considered water supply system in Poland’s Subcarpathian Province. A novel approach to risk analysis of the loss of safety in water supply system taking into account the occurrence of some undesired events was achieved. The estimated value of the risk level, under the given operating conditions, indicates that there is no real threat to water consumers. [ABSTRACT FROM AUTHOR]

Turbidity impacts, not only on the aesthetic properties of water but also on many features capable of affecting health. This leaves the parameter in question as a very important indicator of the quality of surface water (due to a large amount of information on potential threats), and one capable of serving as a basis for risk analysis. Information on the turbidity of raw water was obtained from the water-supply company, with the focus being on data from the years 2010–2015. This reflects a research focus on the period following modernization of a treatment plant, completed in late 2009. Variation in the turbidity of raw water through the annual cycle was analyzed, with the finding that no cessation of delivery of water to the city on account of inadequate quality was necessitated. This further denotes a positive assessment regarding the efficiency of the water-treatment technology installed in 2009, which proved to be very effective at treating water whose turbidity changed rapidly from time to time, to reach several thousand NTUs. The paper also details attempts to determine the “a posteriori” probability of occurrence of turbidity of a certain value, in line with Bayesian theory. [ABSTRACT FROM AUTHOR]

Abstract The work detailed here has sought to analyse the effects of emergency states on water-supply pipelines. For this purpose, a model hydraulic pipe network was created in Epanet 2, on the basis of actual operational data. Using the model, pipeline failures were simulated, and their effects described. The research methodology entails the simulated closure (i.e. failure) of individual pipes in the supply network, as followed by comparative analysis of the distribution of pressure across that network, in failure-free conditions and during a failure. The effects of failure in individual sections could thus be determined, in relation to the area with pressure lowered below the required value, the duration of that pressure reduction, and the potential number of recipients affected by limitation of water supply. The areas most exposed to pressure fluctuations in the water supply as a consequence of pipe-failure are thus pinpointed, with simulation results also serving in in the calculation of indicators for the risk of failure. Highlights • Operating data of the water network functioning in the city are used. • The areas most exposed to pressure fluctuations in the water supply as a consequence of pipe-failure are thus pinpointed. • The method presented, and the results it has generated, provide a basis for quantitative risk testing. [ABSTRACT FROM AUTHOR]

The consequence of the lack of water stability is increased susceptibility in the distribution system to secondary microbial contamination of water and thus a threat to the health of consumers. In this study, three different water quality parameters including BDOC (biodegradable dissolved organic carbon), ΣNinorg, and PO43– were employed to assess and evaluate the risk of loss of biostability of tap water. The analysis was based on the operating data obtained from the water treatment plant (WTP) prior to the final disinfection process for which water is supplied from intake of drilling wells, what constitute the new approach in comparison with other study. In this work, two technological schemes in the WTP were analyzed, one conventional, which is represented as WTPc, and the other using a biologically active carbon filter (BAF), which is represented as WTPcf. The modified Kaplan and Newbold method was used in determining the BDOC content by using for this purpose colonized by autochthonous bacteria bioreactor with granular activated carbon. Results show that conventional water purification processes do not provide the effective elimination of biogenic substances and, in particular, BDOC and assimilable organic carbon, therefore it is recommended to apply BAFs, as its effectiveness in removal of various impurities and the ability to stop waterborne microorganisms is very high. [ABSTRACT FROM AUTHOR]

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The aim of the study is to analyse and assess the water supply network failure frequency in last ten years, with particular emphasis on the last year of the analysis. The analysis is based on actual data obtained from the water company. The study contains the analysis of the network failure with division into used material, the type of network and place of failure occurrence. Also the failure rate was calculated. Continuous changes in the age and material structure of the water network cause the need for conducting failure frequency research because data on failure rate are the key indicators for operational policy of water supply systems. [ABSTRACT FROM AUTHOR]

The aim of this study is to assess the risk of failure of group water network in case of raw water contamination. The analysis was based on qualitative simulation performed in hydraulic water network model developed in the EPANET software. It was focused on the quantitative description of the consequences of chemically contaminated water. The methodology of risk assessment relies in determining the consequences of the supply water containing contamination threatening the health and lives of water consumers. The research methodology is as follows: development of a hydraulic model of the water pipeline and it's hydraulic verification, computer simulations of contamination propagation, calculating the dose delivered to the i-th section of the water supply system supplying water to Ni recipients and the mass of a substance that enters the body li. The simulation results indicate the spread of contamination that after 24 h covered most of the area supplied with water. The load delivered to the resident obtaining water from the i-th section of the water supply network, Li/Ni, was up to 18 g⋅d-1, at least 15 g⋅d-1 was received by 34.9% of the population, 10-15 g⋅d-1 by 12.5% of the residents, 5-10 g⋅d-1 by 10.7% of the residents, 0-5 g⋅d-1 by 41.7% of the residents and uncontaminated water was delivered to only 13.3% of the consumers. The dose taken by the statistical consumer (calculated as for adults) l is up to 0.8 g for Li/Ni = 18 g⋅d-1 and is proportional to Li/Ni. [ABSTRACT FROM AUTHOR]

The paper presents issues related to risks associated with the operation of small water supply systems on the background of water consumer safety assessment made on the basis of risk analysis. Definition of water consumer safety loss as a risk associated with the water consumption of poor quality or water lack was proposed. For this purpose, a three-parameter matrix is implemented with the parameters of the probability of a representative accident scenario, the losses of the water consumers and their protection. Risk management, together with the implementation of protective barriers of small water supply system against threats is a fundamental condition for the continued operation of the system. [ABSTRACT FROM AUTHOR]

The proper operation of a water supply system (WSS) requires constant investment. The priority is to provide residents with high quality potable water, in the required quantity and pressure, in accordance with the applicable regulations. The paper presents an assessment of the potential inherent operational risk of a WSS in support of the risk-based investment management process. It is of high importance to invest in the operational safety as it concerns both producers and consumers. The investment engenders additional costs that should partially be supported by the consumers. Thus, the paper presents a methodology to analyse consumers' readiness to accept water supply services' additional costs. The proposed methods may underpin a comprehensive program for risk-based investment management and operational decision-making. The case study and the approach in this article concern one particular regional WSS, based on information collected from water consumers. The assessment suggests a willingness to tolerate additional costs in view of enhancing the performance of the water supply services. [ABSTRACT FROM AUTHOR]

This paper first presents the results of polling on the subject of potable water in crisis situations, with respondents from south-eastern Poland's Subcarpathian region asked for their opinions on the level of nuisance associated with water supply interruptions and water quality, levels of consumption and water companies' quality of service. Among the respondents 53% regard the quality of the water they receive as satisfactory, while a quarter see it as only average. However, respondents are relatively satisfied with the corporate response when supplies are interrupted, as methods and means of notification are judged effective by 60%. Continuing with work to assess possibilities for water companies to improve their performance in crisis situations, the present study generates an Analytical Hierarchy Process allowing recipients to determine importance criteria where quality of service is concerned. This could facilitate management by water companies, providing for centralised control and comparison that help secure services of appropriate quality. The process can also help protect different groups of recipients, as safety is evaluated through analysis of functioning, and of failures and losses. [ABSTRACT FROM AUTHOR]

The water-supply system is one of the basic and most important critical infrastructures. Water supply service disruption (water quality or quantity) may have serious consequences in modern societies. Water supply service is subject to various failure modes. Failure modes are specified by their degradation mechanisms, criticality, occurrence frequency and intensity. These failure modes have a random nature that impacts on the network disruption indicators, such as disruption frequency, network downtime, network repair time and network back-to-service time, i.e., the network resilience. This paper focuses on the water leakage failure mode. The water leakage failure mode assessment considers the unavoidable annual real water losses and the infrastructure leakage index recommended by the International Water Association's Water Loss Task Force specialist group. Probabilistic statistical modelling was implemented to assess the seasonal index, the failure rates and the expectation value of the "mean time between failures." The assessment is based on real operational data of the network. Specific attention is paid to the sensitivity of failures to seasonal variations. The presented methodology of the analysis of the water leakage failure mode is extendable to other failure modes and can help in developing new strategies in the management of the water-supply system in normal operation and crisis situations. [ABSTRACT FROM AUTHOR]

Given that a consequence of a lack of stability of the water in a distribution system is increased susceptibility to secondary contamination and, hence, a threat to consumer health, in the work detailed here we assessed the risk of such a system experiencing quality changes relating to the biological and chemical stability of water intended for drinking. Utilizing real operational data from a water treatment station, the presented analysis of the stability was performed based on the fault tree method. If they are to protect their critical-status water supply infrastructure, water supply companies should redouble their efforts to distribute stable water free of potentially corrosive properties. To that end, suggestions are made on the safeguarding of water distribution systems, with a view to ensuring the safety of operation and the long-term durability of pipes. [ABSTRACT FROM AUTHOR]

In accordance with the water quality standard, the safe functioning of the water treatment system operation is considered. This paper alludes to extreme situations, which arise where there is periodic deterioration of the quality of raw water, for which the technological process of water treatment is not prepared. A conception method is presented by which to assess indices of risk vis-à-vis drinking water, on the basis of a probability estimation methodology. The categorisation of water pipes in line with quality-reliability as regards the physical and chemical composition of drinking water or water intended for business purposes is proposed. An example of the method being put to use is also offered, and it is recognised how the approach being proposed could be the basis for further analysis that takes different conditions of functioning of water-supply systems into account. [ABSTRACT FROM AUTHOR]