Sanitary sewer overflows (SSO) are becoming of increasing concern in the sewage system management to utilities and regulators. Many overflows are not easily identifiable. If undetected, they can adversely impact public health and are an environmental hazard. The number and severity of SSOs can be reduced through the proper sewerage maintenance and the detection-correction of ongoing events. A methodology is presented to locate meters to maximize the likelihood of detecting a system blockage. When a blockage occurs the discharge rates in the system are affected. If the changes are greater than one would expect due to random variability, they can be attributed to a blockage. The proposed method attempts to optimize the monitoring locations to maximize the number of blockages that can be identified by a given number of meters. The problem is solved using a set-covering approach. The approach allows the tradeoff between the number of detections and cost of gages to be easily assessed. Data from Pima County Wastewater Management's monitoring system is used as a case study. To introduce blockages and analyze system hydraulics a full hydraulic model for the sewer system is applied.