This chapter focuses on the health issues related to the application of Water Saving Systems (WSS) in buildings. It stars by showing the environmental and economic advantages of these systems and then presents the main obstacles to their large-scale implementation: concerns about water quality, the security of the users and the implications on the public infrastructures. For these reasons, it is important to carefully study this question, list all health issues related to the use of WSS and show how they can be minimized and avoided. The base for this chapter is several feasibility studies, made in different types of buildings, and population surveys showing concerns about the user’s security. Studies about water quality in existing WSS are also presented, as well as important security measures presented in international legislation and standards. The conclusions allow us to understand if this question is being properly discussed (if all the main problems are being covered), which measures are being applied and if others are needed.