The critical submergence for dual rectangular intakes with no partition walls was investigated. To predict this critical submergence, the same principles as the available superposition methods developed for multiple pipe intakes were followed. Experiments were conducted on dual rectangular intakes located in different relative positions in an incoming developed canal flow. Multiple (dual) intakes introduce flow blockages on one another's flow. A flow blockage is a type of extra outflow (intake flow) for sink surfaces in addition to the flow of the intake. Because of such an additional suction flow, it is as if the discharge of the intake is increased. Because dual intakes introduce mutual flow blockages and cause more disturbances, the critical submergence is increased. Agreement between the theoretical and experimental results was satisfactory. Depending on the flow and geometrical conditions, the correlation coefficients between the experimental and theoretical results vary from 0.61-0.90. DOI: 10.1061/(ASCE)EY.1943-7897.0000073. (C) 2012 American Society of Civil Engineers.