One of the techniques of artificial intelligence that can be used in risk analysis is fuzzy logic. The use of fuzzy logic brings new values to risk analysis. First, it allows to make calculations for various safety systems because the distribution of input membership function, assumed in the example, can be selected depending on the needs and conditions. The presented method of determining the risk associated with the failure in water supply systems (WSS) was based on the results of study on the operation of water supply networks and the related failures. The implementation of fuzzy logic proposed in this paper allows to determine the failure risk depending on defined by fuzzy functions two parameters: the duration of the lack of water supply and the number of customers without water, and will allow to specify different levels of risk. Due to the large complexity of the individual elements of the WSS and their spatial dispersion, diverse methods of risk assessment are applied (Rak, 2007; Tchorzewska-Cieslak, Rak, 2010; Zimoch, 2009). In all methods both technical aspects and human factors, that have an impact on safety of water supply to the recipient, are considered. Risk assessment tools for water supply have been applied for failure risk assessment in the WSS management, taking into account the consequences of terrorist attacks or natural disasters (Rak, Pietrucha 2008). The functioning safety is associated with analysis of relations between threats, reducing the frequency of their appearing, and, if threats appear, with the identification of their causes and reducing their negative consequences (Valis, 2012). Because of its nature, risk changes the areas of its appearing. Water supply system failures are the result of the civilization development and globalization processes associated with it, which in the significant way influences the WSS functioning, and because of the connection with undesirable events having nonrandom (rare events do not have the statistical stability), but also not-determined character, risk demands specific and interdisciplinary research methods. The aim of this paper is to present the novel approach to risk assessment in combination with failure and consequence analysis, as to evaluate the level of waterworks service availability.
