Comparison of the Antimicrobial Activity of Brass versus Stainless Steel against Opportunistic Premise Plumbing Pathogens

Lead contamination is a significant public health issue as it can cause severe health impacts. Highly publicized instances of elevated lead levels have resulted in regulatory changes to prohibit the use of brass materials in potable water in favor of low-lead alternatives, such as stainless steel. However, there are limited studies investigating their effect on opportunistic premise plumbing pathogens (OPPPs). This study used model plumbing bioreactors, made from either brass or stainless steel, to examine the effects of pipe material and stagnation time on OPPPs, biofilm formation, and lead leaching. The bioreactors were filled with water spiked with OPPPs, Acinetobacter baumannii, Pseudomonas aeruginosa, Mycobacterium avium complex, and Acanthamoeba polyphaga. Each OPPP responded differently to pipe material and stagnation time. Overall, brass had greater antimicrobial activity compared to that of stainless steel. Lead levels exceeding World Health Organization water quality guidelines were found in both brass and stainless steel bioreactors after 10 weeks of stagnation, despite stainless steel being marketed as a low lead alternative. Material analysis found lead deposits on the surface of stainless steel, likely from post manufacturing contamination. These findings demonstrate the need for future research characterizing the influence of plumbing materials on microbial contamination under a range of conditions prior to regulatory changes.