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Maintaining the microbial quality in distribution systems and connected installations remains a challenge for the water supply companies all over the world, despite many years of research. This book identifies the main concerns and knowledge gaps related to regrowth and stimulates cooperation in future research. Microbial Growth in Drinking Water Supplies provides an overview of the regrowth issue in different countries and the water quality problems related to regrowth. The book assesses the causes of regrowth in drinking water and the prevention of regrowth by water treatment and distribution. Editors: Dirk van der Kooij and Paul W.J.J. van der Wielen, KWR Watercycle Research Institute, The Netherlands
Legionnaires' disease, a pneumonia caused by the Legionella bacterium, is the leading cause of reported waterborne disease outbreaks in the United States. Legionella occur naturally in water from many different environmental sources, but grow rapidly in the warm, stagnant conditions that can be found in engineered water systems such as cooling towers, building plumbing, and hot tubs. Humans are primarily exposed to Legionella through inhalation of contaminated aerosols into the respiratory system. Legionnaires' disease can be fatal, with between 3 and 33 percent of Legionella infections leading to death, and studies show the incidence of Legionnaires' disease in the United States increased five-fold from 2000 to 2017. Management of Legionella in Water Systems reviews the state of science on Legionella contamination of water systems, specifically the ecology and diagnosis. This report explores the process of transmission via water systems, quantification, prevention and control, and policy and training issues that affect the incidence of Legionnaires' disease. It also analyzes existing knowledge gaps and recommends research priorities moving forward.
With an increasing population, use of new and diverse chemicals that can enter the water supply, and emergence of new microbial pathogens, the U.S. federal government is faced with a regulatory dilemma: Where should it focus its attention and limited resources to ensure safe drinking water supplies for the future? Identifying Future Drinking Water Contaminants is based on a 1998 workshop on emerging drinking water contaminants. It includes a dozen papers that were presented on new and emerging microbiological and chemical drinking water contaminants, associated analytical and water treatment methods for their detection and removal, and existing and proposed environmental databases to assist in their proactive identification and regulation. The papers are preceded by a conceptual approach and related recommendations to EPA for the periodic creation of future Drinking Water Contaminant Candidate Lists (CCLsâ€"produced every five yearsâ€"include currently unregulated chemical and microbiological substances that are known or anticipated to occur in public water systems and that may pose health risks).
Heterotrophic Plate Counts and Drinking-water Safety provides a critical assessment of the role of the Heterotrophic Plate Count (HPC) measurement in drinking water quality management. It was developed from an Expert workshop of 32 scientists convened by the World Health Organization and the WHO/NSF International Collaborating Centre for Drinking Water Safety and Treatment in Geneva, Switzerland. Heterotrophs are organisms, including bacteria, yeasts and moulds, that require an external source of organic carbon for growth. The HPC test (or Standard Plate Count), applied in many variants, is the internationally accepted test for measuring the hetrotrophic microorganism population in drinking water, and also other media. It measures only a fraction of the microorganisms actually present and does not distinguish between pathogens and non-pathogens. High levels of microbial growth can affect the taste and odor of drinking water and may indicate the presence of nutrients and biofilms which could harbor pathogens, as well as the possibility that some event has interfered with the normal production of the drinking water. HPC counts also routinely increase in water that has been treated by an in-line device such as a carbon filter or softener, in water-dispensing devices and in bottled waters and indeed in all water that has suitable nutrients, does not have a residual disinfectant, and is kept under sufficient conditions. There is debate among health professionals as to the need, utility or quantitative basis for health-based standards or guidelines relating to HPC-measured regrowth in drinking water. The issues that were addressed in this work include: the relationship between HPC in drinking water (including that derived from in-line treatment systems, dispensers and bottled water) and health risks for the general public the role of HPC as an indirect indicator or index for pathogens of concern in drinking water the role of HPC in assessing the efficacy and proper functioning of water treatment and supply processes the relationship between HPC and the aesthetic acceptability of drinking water. Heterotrophic Plate Counts and Drinking-water Safety provides valuable information on the utility and the limitations of HPC data in the management and operation of piped water systems as well as other means of providing drinking water to the public. It is of particular value to piped public water suppliers and bottled water suppliers, manufacturers and users of water treatment and transmission equipment and inline treatment devices, water engineers, sanitary and clinical microbiologists, and national and local public health officials and regulators of drinking water quality.
Recent and forecasted advances in microbiology, molecular biology, and analytical chemistry have made it timely to reassess the current paradigm of relying predominantly or exclusively on traditional bacterial indicators for all types of waterborne pathogens. Nonetheless, indicator approaches will still be required for the foreseeable future because it is not practical or feasible to monitor for the complete spectrum of microorganisms that may occur in water, and many known pathogens are difficult to detect directly and reliably in water samples. This comprehensive report recommends the development and use of a "tool box" approach by the U.S Environmental Protection Agency and others for assessing microbial water quality in which available indicator organisms (and/or pathogens in some cases) and detection method(s) are matched to the requirements of a particular application. The report further recommends the use of a phased, three-level monitoring framework to support the selection of indicators and indicator approaches.Â
Annotation This publication provides a critical analysis of the literature on removal and inactivation of pathogenic microbes in water to aid the water quality specialist and design engineer in making decisions regarding microbial water quality.
Protecting and maintaining water distributions systems is crucial to ensuring high quality drinking water. Distribution systems-consisting of pipes, pumps, valves, storage tanks, reservoirs, meters, fittings, and other hydraulic appurtenances-carry drinking water from a centralized treatment plant or well supplies to consumers' taps. Spanning almost 1 million miles in the United States, distribution systems represent the vast majority of physical infrastructure for water supplies, and thus constitute the primary management challenge from both an operational and public health standpoint. Recent data on waterborne disease outbreaks suggest that distribution systems remain a source of contamination that has yet to be fully addressed. This report evaluates approaches for risk characterization and recent data, and it identifies a variety of strategies that could be considered to reduce the risks posed by water-quality deteriorating events in distribution systems. Particular attention is given to backflow events via cross connections, the potential for contamination of the distribution system during construction and repair activities, maintenance of storage facilities, and the role of premise plumbing in public health risk. The report also identifies advances in detection, monitoring and modeling, analytical methods, and research and development opportunities that will enable the water supply industry to further reduce risks associated with drinking water distribution systems.
Presents a state-of-the-art review of the current technology and applications being utilized to identify sources of fecal contamination in waterways. - Serves as a useful reference for researchers in the food industry, especially scientists investigating etiological agents responsible for food contamination. - Provides background information on MST methods and the assumptions and limitations associated with their use. - Covers a broad range of topics related to MST, including environmental monitoring, public health and national security, population biology, and microbial ecology. - Offers valuable insights into future research directions and technology developments.
Improved housing conditions can save lives, prevent disease, increase quality of life, reduce poverty, and help mitigate climate change. Housing is becoming increasingly important to health in light of urban growth, ageing populations and climate change. The WHO Housing and health guidelines bring together the most recent evidence to provide practical recommendations to reduce the health burden due to unsafe and substandard housing. Based on newly commissioned systematic reviews, the guidelines provide recommendations relevant to inadequate living space (crowding), low and high indoor temperatures, injury hazards in the home, and accessibility of housing for people with functional impairments. In addition, the guidelines identify and summarize existing WHO guidelines and recommendations related to housing, with respect to water quality, air quality, neighbourhood noise, asbestos, lead, tobacco smoke and radon. The guidelines take a comprehensive, intersectoral perspective on the issue of housing and health and highlight co-benefits of interventions addressing several risk factors at the same time. The WHO Housing and health guidelines aim at informing housing policies and regulations at the national, regional and local level and are further relevant in the daily activities of implementing actors who are directly involved in the construction, maintenance and demolition of housing in ways that influence human health and safety. The guidelines therefore emphasize the importance of collaboration between the health and other sectors and joint efforts across all government levels to promote healthy housing. The guidelines' implementation at country-level will in particular contribute to the achievement of the Sustainable Development Goals on health (SDG 3) and sustainable cities (SDG 11). WHO will support Member States in adapting the guidelines to national contexts and priorities to ensure safe and healthy housing for all.