Risk management methods in hot water distribution systems to negate health risks from microbiological contamination

Abstract

Water distribution systems are exposed to a number of risks, i.e. hazards and hazardous events that may result in bad drinking water quality. Microbiological contamination due to e.g. source water contamination, insufficient treatment; backflow and ingress results in a number of annual outbreaks of illnesses in Europe and other countries. In addition to faecally borne pathogens, other microbial hazards (e.g.; toxic cyanobacteria and Legionella) may be of public health importance under specific circumstances (WHO 2007). For efficient risk management, and to avoid sub-optimization of measures, a holistic view of the water supply system is needed, since hazards in one part of the system may lead to consequences in another part (TECHNEAU 2010). The primary aim of this article is to present our research focused on theoretical and experimental analysis of hot water distribution systems from the point of view of microbiological risk using risk management methods. Case studies show that the water heater tank was identified as a source of microbiological contamination - Legionellas. A simulation model of temperature and water velocity was prepared to avoid the risk of infection. Water temperature is one of the risk factors that encourages the bacterial growth, so we simulated the layering of temperature in boiler by using the software Fluent 6.3