Water temperature is often monitored at water sources and treatment works; however, there is limited monitoring of the water temperature in the drinking water distribution system (DWDS), despite a known impact on physical, chemical and microbial reactions which impact water quality. A key parameter influencing drinking water temperature is soil temperature, which is influenced by the urban heat island effects. This paper provides critique and comprehensive summary of the current knowledge, policies and challenges regarding drinking water temperature research and presents the findings from a survey of international stakeholders. Knowledge gaps as well as challenges and opportunities for monitoring and research are identified. The conclusion of the study is that temperature in the DWDS is an emerging concern in various countries regardless of the water source and treatment, climate conditions, or network characteristics such as topology, pipe material or diameter. More research is needed, especially to determine (i) the effect of higher temperatures, (ii) a legislative limit on temperature and (iii) measures to comply with this limit.
Abstract. This article deals with sensitivity analysis of real water consumption in an office building. During a long-term real study, reducing of pressure in its water connection was simulated. A sensitivity analysis of uneven water demand was conducted during working time at various provided pressures and at various time step duration. Correlations between maximal coefficients of water demand variation during working time and provided pressure were suggested. The influence of provided pressure in the water connection on mean coefficients of water demand variation was pointed out, altogether for working hours of all days and separately for days with identical working hours.
Pressure management is the basic step of reducing water losses from water supply systems (WSSs). The reduction of direct water losses is reliably achieved by reducing pressure in the WSSs. There is also a slight decrease in water consumption in connected properties. Nevertheless, consumption is also affected by other factors, the quantification of which is not trivial. However, there is still a lack of much relevant information to enter into this analysis and subsequent decision making. This article focuses on water consumption and its prediction, using regression models designed for an experiment regarding an administrative building in the Czech Republic (CZ). The variables considered are pressure and climatological factors (temperature and humidity). The effects of these variables on the consumption are separately evaluated, subsequently multidimensional models are discussed with the common inclusion of selected combinations of predictors. Separate evaluation results in a value of the N 3 coefficient, according to the FAVAD concept used for prediction of changes in water consumption related to pressure. The statistical inference is based on the maximum likelihood method. The proposed regression models are tested to evaluate their suitability, particularly, the models are compared using a cross-validation procedure. The significance tests for parameters and model reduction are based on asymptotic properties of the likelihood ratio statistics. Pressure is confirmed in each regression model as a significant variable.
The article is focused on the description of problems that can be caused by increased temperature of drinking water in public drinking water distribution system (DWDS). Increased water temperature is an actual issue that the water industry has had to address in recent years, particularly as a result of the ongoing climate change. In recent years, long periods with high air temperatures have been more frequent than before. High air temperatures warm soil horizons and this results in an undesirable increase in drinking water temperature in water mains. Temperature is a physical, sensible indicator of water quality that affects a variety of chemical, biological, and microbiological processes in water. Therefore, the optimum temperature range of 8-12 ° C, which is to be achieved by the drinking water in the DWDS, is set by Decree of Ministry of Health of the Czech Republic no. 252/2004 Coll. Long-term high level of water temperature also contributes, among other things, to the development of the microbiological component of water in the DWDS and to the deterioration of organoleptic characteristic such as unpleasant odour or taste. The paper summarizes the technical regulations that are designed to provide the recommended water temperature in the DWDS, as well as the specific consequences and operating faults that may occur when water temperature is outside the optimum range of values. In view of the conclusions of available studies focused on predicting the future climate in the Czech Republic, it can be assumed that in the near future more frequent problems of operation can be expected in water supply systems due to unacceptable drinking water temperature. Above all, there will be water quality disturbances involving temporary deterioration of organoleptic, biological and microbiological indicators.
This paper outlines one possible approach to the comprehensive technical audit of water distribution networks. Based on practical experience, discussions with domestic and foreign operators, and knowledge gained from international projects, the paper proposes technical indicators, methods for their determination and criteria for evaluating the values reached by these indicators. The proposed procedure is based on the FMEA (Failure Modes Effects and Analysis) method, used in the general theory of risk analysis. The results of this method were employed to evaluate the technical condition of the water distribution network in Pilsen, Czech Republic.
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