In this article, risk management and Legionella prevention is discussed from a practice-oriented point of view, which can be assigned to Facility Management in healthcare (FM in HC). Water systems in facilities contaminated with Legionella is a serious issue of hygienic risk which needs to be addressed and not only of economic threat or image loss to a facility. Managers, such as operators or any other duty holders, can be responsible for building-associated facilities (water systems). This paper collects, extracts and discusses FM-relevant duties. It emphasizes important issues with relevance to risk management. First, a tabulated collection of statutes, standards and other documents guiding for design, operation and maintenance to minimise risks caused by Legionella in building (drinking) water systems is presented. This is followed by well-discussed situations reported from practice in the national context of Germany. The topic of Legionella prevention of water systems is not limited to a national context. Differences exist according to legislation and to explanations of generally accepted engineering standards, i.e. norms, recommendations, or technical and guidance documents. For the people responsible, who may be assigned to the professional field of FM, there are undeniably aspects of water hygiene that could enforce criminal and civil law obligations. The results of this context-specific paper may provide support in detecting deficiencies and thus avoid potential lawsuits.