Improved sensing and monitoring is needed for effective environmental applications such as microbial water quality monitoring. The presence and quantity of indicator organisms such as Escherichia coli or Enterococcus faecalis are monitored to infer the probable extent of faecal contamination. Traditional approaches to biosensor optimisation focus on specific physical aspects of the system (such as electrode material), without applying a more holistic perspective. We have developed an E. coli detector based on a screen-printed electrode (SPE) bioelectrochemical system that can be used in a small volume set up, which lowers detection time after volume reduction. We applied a statistical assessment method targeting improved detection of a simulated sample from a concentration device. Our aim is to more completely understand device performance limitations and develop system improvements based on such insights.