In the paper the issue of failure risk assessment in water supply system (WSS) was presented. Problems of water supply network failure constitute a crucial issue in waterworks practice. The results of the analysis were obtained on the basis of real data from water network operation. Attention has been paid to the problem of risk assessment in the context of risk acceptance criteria. An example of criteria application was shown for the exemplary water supply network. The water network indicators: failure frequency, time of failure removal, repair time and intensity of renewal, were calculated. The obtained information was used to describe the general characteristics of the examined system and the technical conditions of the WSS. The performed analysis can be used in the assessment of future failure prediction of the water supply network.