The determination of toxic pesticides in drinking water is an ongoing matter of public safety. Pesticides can enter tap water through various sources such as industrial/agricultural waste and urban runoff. Municipal laboratories face challenges in handling large sample volumes and require efficient mass spectrometry-based methods to overcome compound coelution during short analysis times. This application note reports the results of the analysis of 76 organochlorine, organonitrogen, organophosphorus pesticides and related isomers performed with the PerkinElmer GCMS 2400™ System with PerkinElmer Elite 5MS capillary column. The method presented in the application note shows a GC/MS optimized approach minimizing coelution of problematic compounds, and compliant to the requirements of EPA method 525.23 and 525.34 with reduced analysis time.