The present paper is mainly concerned with pipe system failure probability estimation. For this purpose, a multiple component dependent failure (MCDF) model is introduced to deal with dependency among pipe segment failures. The MCDF model is directly derived from load-strength interference analysis with the underlying notion that stochastic environment load brings about failure dependency. The influence of pipe segment failure dependency on pipe system failure probability is addressed and a modified system failure probability model is presented. It is also shown that, with regard to a pipe system, the multiple failures of pipe segment leaks might lead to a pipe system disabling leak or even to a break. The probability of pipe system disabling leak or break induced by the imultaneous failures of multiple segment leaks is estimated by means of the MCDF model. The estimation results indicate that pipe system failure probability depends not only on the mean values of the respective segment failure probability random variables, but also on other distribution parameters (e.g., the standard deviations) of them. Pipe system failure probability estimated by means of the modified model is sometimes several times lower than that estimated by the conventional system failure probability model.