The effects of dimensions and relative positions of two (a dual) pipe intakes on the critical submergence are investigated. A dimensional analysis provided the relationship between the critical submergence and the governing dimensionless variables. Also, the potential flow solution was utilized to predict the critical submergence(s) for dual pipe intakes without partition walls located in the canal axis. Experiments were conducted on two vertical intakes at various relative positions. The experimental results indicate that the critical submergence is considerably affected by the relative positions and dimensions of an intake. The critical submergence for dual pipe intakes is larger than that of a single intake under identical conditions. The agreement between the potential flow solution and the experimental data related to the dual intakes on the same axis as the canal flow was found to be good.