Despite numerous legionellosis outbreaks worldwide attributed to contaminated engineered water systems (EWS), suitable tools for assessing control measures in EWS are lacking. We hypothesise that Legionella mobility and persistence in EWS can be evaluated using surface-modified, DNA-encapsulated biopolymer microparticles that have similar physicochemical properties to Legionella pneumophila. Our preliminary work has shown promising results. In this study, we will validate these novel microparticles for their suitability as a model alongside L. pneumophila in different plumbing materials and biofilms. The novel Legionella surrogate is a world-first that can be used in operational EWS as it comprises biocompatible materials. Our novel approach will reduce reliance on risky, expensive and labour-intensive Legionella analyses, and it will represent L. pneumophila more accurately than the traditionally used Escherichia coli indicator. The research findings will provide safe in-situ performance validations of control measures that will reduce legionellosis risks and inform better EWS design, thereby improving public health.