A method includes receiving, by a processing device and from one or more sensors coupled to a water reservoir storing water received from a separator, fluid information. The fluid information includes a water level of the water reservoir. The separator is fluidically coupled to a wellbore string disposed within a wellbore. The method also includes determining, based on the fluid information, operation mode instructions. The method also includes transmitting, to a controller communicatively coupled to at least one flow regulation device fluidically coupled to the wellbore string, the operation mode instructions. The controller controls, based on the instructions, the at least one flow regulation device to regulate, during a production mode of the wellbore string, a flow of production fluid from the wellbore string to the separator or regulating, during a water injection mode of the wellbore string, a flow of water from the water reservoir into the wellbore string.