The safety of a population also relies on the safety of the water pipe network systems. Good quality water supplying is required. A failure of these types of systems may have a huge social impact. The theory of vulnerability of water pipe networks intends to give a contribution in this context by tracing the vulnerable parts of the system and, consequently, giving guidance to increase its robustness. This theory is described in brief and supported on three water pipe networks examples. (C) 2011 Elsevier Ltd. All rights reserved.