Causes of waterborne outbreaks in community water systems in Finland: 1980-1992

1995 ◽  
Vol 31 (5-6) ◽  
pp. 33-36 ◽  
Author(s):  
K. Lahti ◽  
L. Hiisvirta
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
Water Distribution ◽  
Water Source ◽  
Distribution Networks ◽  
Etiologic Agent ◽  
Chlorinated Organic Compounds ◽  
Water Supplies ◽  
Community Water Systems ◽  
Etiologic Agents

Finland is known as a country with thousands of unpolluted lakes and pristine groundwaters. For this reason treatment processes applied in the drinking-water industry are quite simple. These kinds of water supplies, as well as private wells, are vulnerable for accidental pollution, leading to twenty-four reported waterborne epidemics outbreaks in Finland in 1980-1992. About 40 per cent of these outbreaks were due to contaminated water from community drinking-water supplies. The number of people affected in these outbreaks was around 7 700. Contaminated groundwater was a more common cause than surface water. The majority of Finnish groundwater supplies distribute water without any treatment or only with alkalization. In most outbreaks leakage and blockage of a sewage pipe in the vicinity of a groundwater well resulted in the contamination of drinking-water. The largest of these outbreaks affected some 5 000 people. The etiologic agents in these epidemics were most probably viruses; faecal indicator bacteria and enteric viruses were detected in water samples during the epidemics. Contamination of water distribution networks due to cross-connection caused two restricted epidemics. Inadequate disinfection of surface water was the reason for three outbreaks. Two of these were caused by the same water supply in subsequent years. The raw water source for this supply was of quite a high quality, for which reason the treatment consisted only of rapid sand filtration and chlorination. For fear of the chlorinated organic compounds formed during disinfection the amount of chlorine in water treatment was reduced to a level where disinfection was inadequate, and some hundred people became ill. The etiologic agent in these outbreaks remained unknown.

scholarly journals Pemanfaatan Sistem Informasi Geografis Dalam Evaluasi Kinerja Penyediaan Air Minum Perpipaan (Studi Kasus Sistem Lendah Kabupaten Kulon Progo)

2018 ◽  
Vol 10 (1) ◽  
pp. 14
Author(s):  
Angga Budi Kusuma
Keyword(s):  
Drinking Water ◽  
Water Distribution ◽  
Water Pressure ◽  
Water Source ◽  
Distribution Networks ◽  
Geographic Information ◽  
Accurate Information ◽  
Pipe Network ◽  
Network Evaluation ◽  
Pressure Reducing Valve

Abstrak Evaluasi jaringan perpipaan merupakan bagian dari evaluasi kinerja penyediaan air minum. Sistem Informasi Geografis (SIG) memberikan informasi akurat mengenai informasi kebumian dan integrasinya dengan Epanet memberikan efisiensi dalam evaluasi jaringan perpipaan. Jaringan Perpipaan Sistem Lendah merupakan jaringan distribusi air minum dengan sistem pompa-gravitasi dengan sumber air baku Sungai Progo. Hasil analisis menunjukan bahwa Sistem Lendah mampu menyediakan kebutuhan air minum selama 24 jam. Sisa tekanan air di beberapa lokasi sangat tinggi diatas persyaratan menyebebabkan rentan kebocoran. Kecepatan aliran di beberapa ruas pipa masih dibawah kecepatan yang dipersyaratkan menyebabkan potensi pengendapan dalam pipa. Beberapa solusi dapat digunakan untuk mengatasi permasalahan tersebut dengan mengganti jenis pipa, mengganti diameter pipa sesuai dengan kriteria, menambahkan bak pelepas tekanan (BTP) atau pressure reducing valve (valve) untuk mengurangi sisa tekanan di beberapa titik. Kata Kunci: Sistem Informasi Geografis, Epanet, Sistem Lendah, Jaringan PerpipaanAbstractPipe network evaluation is a part of evaluation of drinking water supply performance. Geographic Information System (GIS) provides accurate information about earth and its integration with Epanet gives eficiency in pipe network evaluation. Lendah system pipe network is drinking water distribution networks with pump-gravitation system and water of Progo River as the water source. The analyst shows that Lendah System is capable of providing drinking water needs 24 hours daily.The remaining water pressure in several locations are exceeded standard causing leakage vulnerability. Water velocity of several pipe segments is below required velocity. Several solutions could be taken to solve those problems they change pipe type, change pipe diameter suited to standard, add pressure release tube (PRT) or pressure reducing valve (valve) to reduce remaining pressure in several nodes. Keywords: Geographic Information Systems, Epanet, Lendah System, Pipe Network

scholarly journals Application of DVC-FISH method in trackingEscherichia coliin drinking water distribution networks

2012 ◽  
Vol 5 (1) ◽  
pp. 515-532
Author(s):  
L. Mezule ◽  
S. Larsson ◽  
T. Juhna
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Surface Water ◽  
Water Samples ◽  
Water Distribution ◽  
Large City ◽  
Distribution Networks ◽  
Water Distribution Networks ◽  
E Coli ◽  
Drinking Water Distribution

Abstract. Sporadic detection of live (viable) Escherichia coli in drinking water with molecular methods but not with standard plate counts has raised concerns about the reliability of this indicator in the surveillance of drinking water safety. Previous studies have shown that in low numbers metabolically active E. coli can be found in the biofilm of drinking water. The aim of this study was to analyse the distribution of non-cultivable E. coli in the drinking water distribution system meeting microbiological quality standards and evaluate the importance of the biofilm as its harbour. In total 24 biofilm samplings and 40 at least 100 times pre-concentrated water samples were taken over a period of two years from two water treatment plants (surface water and groundwater) and four locations in water distribution network of a large city. Cultivable, total and able to divide (viable) E. coli concentration was measured in all samples. The results showed that none of the network biofilm samples contained cultivable E. coli and less than two cells per 10 l were detected in the pre-concentrated water samples. However, almost all of the samples contained viable E. coli in the range of 1–50 cells per litre or cm2 which represented approximately 53% of all E. coli detected. The amount of viable E. coli was higher in the biofilm after surface water treatment when compared to the outlet from the groundwater plant and the number tended to increase from both treatment plants further into the network irrespective of the season. In conclusion, E. coli in the water supply is not necessarily directly linked to recent faecal contamination and tends to accumulate in the networks where it is less exposed to disinfectants. Thus it can be accepted that biofilm formation in the drinking water distribution networks increases the risk of accumulation of viable but not cultivable E. coli in the system.

Estimation of the variability of the chemical composition of drinking water transported by water distribution networks

2020 ◽  
Author(s):  
М.Ю. Вождаева ◽  
А.Р. Холова ◽  
И.А. Мельницкий ◽  
И.И. Белолипцев ◽  
Н.В. Труханова ◽  
...  
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
Water Distribution ◽  
Distribution Networks ◽  
Water Distribution Networks ◽  
Sampling Point ◽  
Factors Affecting ◽  
Dead End ◽  
General Chemical ◽  
Range Of Variation

При оценке надежности и эффективности работы предприятий водопроводно-канализационного хозяйства повышенного внимания требует транспортировка питьевой воды до потребителя из-за возможного ухудшения ее качества при длительном времени транспортирования, а также в тупиковых и локальных застойных зонах распределительных сетей. Выявлено, что значения общехимических показателей в питьевой воде при ее транспортировке достаточно стабильны. Исключение составляют мутность питьевой воды поверхностного водозабора и жесткость питьевой воды инфильтрационного водозабора. Статистические критерии, полученные при обработке многолетних данных (диапазон варьирования концентраций металлов, стандартное отклонение и форма графиков плотности распределения их концентраций), свидетельствуют о большей стабильности состава питьевой воды в сетях по сравнению с водой в резервуаре чистой воды на водозаборах. Близкое к нормальному распределение значений концентраций выбранных показателей говорит об отсутствии значимых случайных факторов, влияющих на качество воды в сетях. Тупиковые и локальные застойные зоны сетей являются уязвимыми для коррозионных процессов, происходящих внутри труб, что подтверждается более высокими значениями индекса Ланжелье для воды, отобранной в этих зонах. В целом питьевая вода поверхностного водозабора характеризуется большим разбросом концентраций компонентов и является более коррозионно-активной по сравнению с водой инфильтрационного водозабора. В воде застойных и тупиковых зон водораспределительных сетей наблюдается увеличение содержания железа, цинка, мутности. Относительно действующих на сегодняшний день нормативов качества воды значения концентраций находятся на стабильном приемлемом уровне во всех точках отбора, что подтверждается диапазоном варьирования концентраций, охватывающим весь период наблюдения (2006–2016 годы). While estimating the reliability and efficiency of water supply and sanitation utilities, transporting drinking water to the consumer requires closer attention due to possible quality deterioration during long transportation time, as well as in dead-end and local stagnant zones of distribution networks. It was revealed that the values ​​of the general chemical indicators in drinking water during its transportation are quite sound. An exception is the turbidity of drinking water from surface water intakes and the hardness of drinking water from infiltration water intakes. Statistical criteria obtained during long-term data processing (the range of variation in metal concentrations, standard deviation and the shape of the density distribution graphs of their concentrations) evidence greater stability in the composition of drinking water in networks compared to water in clean water tanks at water intakes. A close to normal distribution of the concentration values of the selected indicators suggests the absence of significant random factors affecting the quality of water in the networks. Dead ends and local stagnant zones of networks are exposed to corrosion processes occurring inside pipes, which is confirmed by higher values of the Langelier index in water samples from these zones. In general, drinking water from surface water intakes is characterized by a wide scatter in the concentrations of the components and is more corrosive compared to the water from infiltration water intakes. Water in stagnant and dead-end zones of water distribution networks has raised turbidity and contains increased concentrations of iron and zinc. Relative to the current water quality standards, the concentration values were at a stable acceptable level in any sampling point, which is confirmed by the range of variation in concentrations during the whole observation period (2006–2016).

The assessment of biofilm community composition on plumbing materials in filtered and unfiltered water distribution systems

2003 ◽  
Vol 3 (1-2) ◽  
pp. 187-191
Author(s):  
M.M. Critchley ◽  
N.J. Cromar ◽  
H.J. Fallowfield
Keyword(s):  
Drinking Water ◽  
Fatty Acid ◽  
Community Composition ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Polymer Materials ◽  
Fatty Acid Profiles ◽  
Water Supplies ◽  
Drinking Water Distribution Systems

Biofilms have been extensively characterised within drinking water distribution systems. However, the significance of materials on biofilm species diversity is not established. This study investigated the community composition of biofilms on plumbing materials receiving filtered and unfiltered water supplies. Biofilms were extracted from polybutylene, polyethylene, cross-linked polyethylene, unplasticised polyvinyl chloride and copper tubes in sampling rigs receiving Murray-Onkaparinga water before or after filtration. Biofilms were extracted and analysed for fatty acid composition using the FAME™ methodology. There were differences in the fatty acid profiles of biofilms and the respective water supplies, indicating differences in the attached and planktonic communities. The results also showed significant differences in the fatty acid profiles of biofilms on the polymer materials compared to copper, suggesting variations in biofilm populations on the different materials. The potential for materials to select for microbial populations has significant implications for the ecology of drinking water biofilms.

Improving water age estimation in a drinking water distribution network by field study and digital modeling

2021 ◽  
Author(s):  
Jon Kristian Rakstang ◽  
Michael B. Waak ◽  
Marius M. Rokstad ◽  
Cynthia Hallé
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Network Model ◽  
Age Estimation ◽  
Water Distribution ◽  
Distribution Network ◽  
Distribution Networks ◽  
Plate Count ◽  
Water Age ◽  
Drinking Water Distribution

<p>Municipal drinking water distribution networks are complex and dynamic systems often spanning many hundreds of kilometers and serving thousands of consumers. Degradation of water quality within a distribution network can be associated to water age (i.e., time elapsed after treatment). Norwegian distribution networks often consist of an intricate combination of pressure zones, in which the transport path(s) between source and consumer is not easily ascertained. Water age is therefore poorly understood in many Norwegian distribution networks. In this study, simulations obtained from a water network model were used to estimate water age in a Norwegian municipal distribution network. A full-scale tracer study using sodium chloride salt was conducted to assess simulation accuracy. Water conductivity provided empirical estimates of salt arrival time at five monitoring stations. These estimates were consistently higher than simulated peak arrival times. Nevertheless, empirical and simulated water age correlated well, indicating that additional network model calibration will improve accuracy. Subsequently, simulated mean water age also correlated strongly with heterotrophic plate count (HPC) monitoring data from the distribution network (Pearson’s R= 0.78, P= 0.00046), indicating biomass accumulation during distribution—perhaps due to bacterial growth or biofilm interactions—and illustrating the importance of water age for water quality. This study demonstrates that Norwegian network models can be calibrated with simple and cost-effective salt tracer studies to improve water age estimates. Improved water age estimation will increase our understanding of water quality dynamics in distribution networks. This can, through digital tools, be used to monitor and control water age, and its impact on biogrowth in the network.</p>

scholarly journals Technical note: Problem specific variators in a genetic algorithm for the optimization of drinking water networks

2018 ◽  
Author(s):  
Karel van Laarhoven ◽  
Ina Vertommen ◽  
Peter van Thienen
Keyword(s):  
Drinking Water ◽  
Real World ◽  
Water Distribution ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Technical Note ◽  
Practical Implementation ◽  
Utility Level ◽  
Water Utility ◽  
Drinking Water Distribution

Abstract. Genetic algorithms can be a powerful tool for the automated design of optimal drinking water distribution networks. Fast convergence of such algorithms is a crucial factor for successful practical implementation at the drinking water utility level. In this technical note, we therefore investigate the performance of a suite of genetic variators that was tailored to the optimisation of a least-cost network design. Different combinations of the variators are tested in terms of convergence rate and the robustness of the results during optimisation of the real world drinking water distribution network of Sittard, the Netherlands. The variator configurations that reproducibly reach the furthest convergence after 105 function evaluations are reported. In the future these may aid in dealing with the computational challenges of optimizing real world networks.

scholarly journals GAP FILLERS OR PIONEERS: INFORMAL WATER SUPPLIERS IN PERI-URBAN AREAS OF THE TECHIMAN MUNICIPALITY OF GHANA

2021 ◽  
Vol 8 (1) ◽  
pp. 525-539
Author(s):  
Lydia Kwoyiga
Keyword(s):  
Urban Areas ◽  
Water Distribution ◽  
Water Source ◽  
Water Quality Monitoring ◽  
Distribution Networks ◽  
Sub Saharan Africa ◽  
Formal Sector ◽  
Public Provision ◽  
Sub Saharan ◽  
Municipal Assembly

There is continuous expansion and growth of urban and peri urban areas in Sub-Saharan Africa with projections indicating that this will double. Some peri-urban areas such as those in the Techiman municipality of Ghana are experiencing this trend. Nonetheless, the spate of growth of these areas outstrips the supply of utilities by municipal water distribution networks. As a result, some areas have little or no public provision. In order to address the water supply challenge, places with favourable hydrological settings are witnessing the emergence of informal water suppliers as “gap fillers” or “pioneers”, providing water services. Noteworthy, however, existing studies about informal water suppliers in peri-urban areas in Ghana lump them together, without considering the water source. This study differs in that it specifically examines the evolution and the features of informal water suppliers who privately and independently abstract and supply groundwater. Additionally, it attempts to understand the nature of informality of the suppliers and the possibility of formalisation. The paper is an exploratory study using the case of private mechanised borehole operators who supply water in their respective areas. The findings showed that in some peri-urban areas in the Techiman municipality, some dwellers constructed and operated mechanised boreholes, which provide in-situ water and utilities to others. They are mostly pioneer water suppliers in some of the areas. Their services are informal by nature because they are largely independent of the formal sector and apply informal arrangements in rendering their services. Seen also as business enterprises, they are not licenced. However, the boreholes are registered with the Municipal Assembly, which indicated some level of formalisation. The study recommended that efforts to formalise them further should focus on improving water quality monitoring for consumption and promoting sustainable abstraction.

scholarly journals Assessing efficiency of pre-ammonization aimed at reducing carcinogenic risks caused by trihalomethanes in drinking water

2020 ◽  
pp. 70-77
Author(s):  
L.A. Deryabkina ◽  
◽  
B.I. Marchenko ◽  
N.K. Plugotarenko ◽  
A.I. Yukhno ◽  
...  
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
Natural Water ◽  
Water Source ◽  
Water Disinfection ◽  
Residual Chlorine ◽  
Gas Liquid Chromatography ◽  
Initial Water ◽  
Organic Chlorine ◽  
Deep Purification

In most Russian regions there is still a pressing issue related to providing population with high quality and safe drinking water. Up to now, chlorination has been the primary technique applied to disinfect drinking water as it is highly efficient, reliable, and relatively cheap. However, when chlorine is used to disinfect natural water that contains organic pollutants, it results in risks of by-products occurrence. These products are trihalomethanes, epigenetic carcinogenesis promoters that cause elevated carcinogenic risks under oral, inhalation, and subcutaneous exposure. Our research goal was to hygienically assess efficiency of pre-ammonization applied in water treatment procedures in order to prevent occurrence of carcinogenic organic chlorine compounds during chlorination and to minimize carcinogenic risks. We determined trihalomethanes and residual chlorine contents in model samples of natural water taken from a surface water source after chlorination with different doses of chlorine. We examined 52 pair parallel samples that had undergone pre-ammonization with ammonia sulfate and control ones. Trihalomethanes concentrations were determined in model water samples with gas-liquid chromatography. Basing on the results obtained via experiments on laboratory chlorination of river water, we determined quantitative characteristics and built regression models showing dependence between concentrations of organic chlorine compounds occurring due to chlorination (chloroform, dichlorobrommethane, dibromchloromethane) and chlorine doses and preammonization parameters. It was established that pre-ammonization was the most efficient in terms of preventing trihalomethanes occurrence under such disinfection modes when contents of residual active chlorine didn’t exceed recommended levels (0.8–1.2 mg/L). Basic ways to minimize carcinogenic risks caused by trihalomethanes are systemic control over their contents in drinking water during social and hygienic monitoring procedures; preliminary ammonization of water taken from surface water sources; prevention of unjustified hyper-chlorination; preliminary deep purification of initial water; disinfection with ultrasound radiation instead of preliminary chlorination; etc.

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