Modern management of water supply systems is based on a preventive strategy consisting of the prevention of failures and crisis situations. Water pipe failures resulting in a lack of water supply for a long period pose a threat to the water consumers safety. The aim of the work was to present the methodology and develop a risk map of lack of water supply to consumers. The article presents a failures simulation of the main pipes transporting treated water from the water treatment plant to the city carried out using the EPANET 2.0. software. The simulation results made it possible to determine the consequences of failures by determining the number of inhabitants (consumers) affected with lack of water supply as a result of failure of the main pipes near the water treatment plant WTP which, together with the failure rate, were used to prepare risk maps of lack of water supply. The developed method was presented on the water supply network located in Central and Eastern Europe. It was found that the highest risk of lack of water supply is related to the failure of the M3 main pipe, which transports water to the eastern and north-eastern parts of the city. It is recommended to modernize the M3 main pipe, which will reduce the number of failures resulting in a lack of water supply.

Background: Specialist literature indicates a large share of the human factor among the causes of failure of technical systems at the level of 70 to 90%, which depends on the sector studied. The collective water supply system is an anthropotechnical system, i.e., it is a complex connection between man and the technical system resulting from the deliberate influence of man on the technical system. Methods: The work presents an assessment of operator reliability of a selected water treatment process based on the fault tree analysis (FTA). Elementary events are determined by the operator’s error probability. Results: A failure tree was prepared for the peak event of the filter station failure, resulting from an operator’s error during the filter washing procedure. The probability of a peak event occurring is 0.0580. Conclusions: The developed fault tree allows for the identification of elementary events leading to an emergency event. The operator fulfills its task of maintaining the continuity of water treatment.

The approaching prospect of obligatory implementation and pursuit of Water Safety Plans forces water companies to reflect on supplies in crisis situations that, for example, relate to the closure of a basic intake, or scarcity of water due to climates changes (droughts). Where supplies are diversified, there can be greater certainty as to the continuity of good quality supply, even in an emergency. As one of each country’s systems of critical infrastructure, the collective water supply system (CWSS) should be protected, with the diversification of supply treated as a basic tool to raise levels of security among consumers. This article, therefore, presents a method from the authors’ by which diversification may be assessed, including by reference to basic and key elements of the CWSS capable of affecting the continuity of water supply. Sample calculations using the proposed method are also presented here for selected Polish cities. In the event, as only one Polish CWSS can be assigned to the category representing excellent diversification, the suggestion is clearly that Poland’s systems must still progress with the diversification of water supply, in order to further reduce the risk of water shortages.

Since 2017, risk assessments for water intakes in Poland have provided the basis for decisions to establish indirect water protection zones. The preventive, risk-based approach and the related risk minimization measures are required under the provisions of the Drinking Water Directive (DWD) of the European Parliament and of the Council of 16 December 2020 on the quality of water intended for human consumption. This approach is in line with the World Health Organization (WHO) recommendations for water safety plans. The aim of this study was to present a methodology and to carry out a risk assessment of the threats to surface water intakes, which in Poland, should be completed by the end of 2022. Risk assessments were performed for four onshore-type surface water intakes located in south-eastern Poland. The results were presented in aggregate form, which enabled clear presentation and conclusions. It was found that the greatest risks are associated with seasonal changes in water quality (mainly high turbidity and water blooms), unregulated sewage management, the occurrence of floodwater flows and catastrophic events caused by the potential failure of wastewater treatment plants. Based on the results of the risk assessment, the need to establish new, or to adjust the existing, protection zones for the analyzed water intakes was identified.