Pollution in water resources is rising high due to over-exploitation and lack of purity and freshness around water bodies, which includes dumping of organic/industrial substances or fecal sludge threatening the human and animal population. Detecting bacterial contamination in water using an electrochemical-based sensor can be an effective approach. Coliform bacteria are abundantly present in wastewater, with Escherichia coli being one of the major types. Graphene oxide has shown promising results in sensor development. The interaction between graphene oxide and E. coli dilutions from 10^-1 to 10^-10, upon incubating with 3% H2O2 v/v, results in a change in voltage in the source measuring unit. In this study, an electrochemical sensor is prepared using a graphene oxide-coated screen-printed electrode for the detection of catalase-positive E. coli bacteria in water samples based on the breakdown of H2O2. The LOD and LOQ for the electrochemical system were recorded as 2.851 CFU/ml and 8.641 CFU/ml, respectively, with a sensitivity of 5.1467 mV CFU/ml for E. coli. The sensor response time is within milliseconds. These properties make our system efficient and reliable for detecting coliform bacteria in water samples.