A heuristic approach for system reliability of water distribution system (WDS) is presented. Reliability nodes, estimated through extended-period simulation using node-head analysis that predicts the availability of pressure head at all nodes during three demand flow patterns express the system reliability. In this study, the performance of an integrated WDS is investigated under four drought response actions: (1) reducing nodal demand up to 30 %; (2) increasing the Hazen- William’s roughness coefficient up to 30 %; (3) increasing pipe sizes up to 4 in. (100 mm); and (4) all of these actions collectively. Results illustrate that the use of reliability bounds to estimate the integrated WDS reliability is a power full technique for water systems involving multiple condition modes. This analysis provides a set of guidelines for WDS managers and designer to improve system performance.