Musk fragrances have been detected in drinking water (DW) at trace concentrations. However, their impact on the microbial quality of DW has been disregarded. This work provides a pioneer evaluation of the effects of two synthetic musks contaminants, tonalide (AHTN) and galaxolide (HHCB), in microbial biofilms formed on two different surfaces, polyvinyl chloride (PVC) and stainless steel AISI 316 (SS316). Three bacterial species isolated from DW (Acinetobacter calcoaceticus, Burkholderia cepacia and Stenotrophomonas maltophilia), were used to develop 7-day-old single and mixed species biofilms. The impact of musks was assessed directly on biofilms but also on the bacteria motility, biofilm formation ability and biofilm susceptibility to chlorination. AHTN musk caused the most remarkable effects by increasing the cellular density and viability of mixed biofilms, and the extracellular polysaccharides content of biofilms on SS316. Most of the alterations caused by the direct exposure of biofilms to musks were observed when SS316 was used as an adhesion surface. In contrast, the ability to form biofilms and their susceptibility to chlorine were more affected for bacteria from HHCB-exposed biofilms on PVC. The overall results demonstrate that the presence of musks at residual concentrations influences DW bacterial dynamics, with the potential to impact the DW quality and safety. The type of plumbing material may further impact the effects of musks.