Consumption of lead has been linked to severe health conditions such as kidney damage and interference in calcium metabolism for bone formation with infants, foetuses and pregnant women being most susceptible. Highly publicised instances of non-compliance of lead levels in drinking water at the Perth Children’s Hospital in Western Australia and Flint Michigan water crisis, has resulted in regulatory changes that prohibit the use of brass in potable water infrastructure in favour of low-lead alternatives such as stainless steel. Although switching fittings may minimise the risk of lead exposure, there is limited evidence describing the effects of low lead alternatives on microbial water quality. Closed system biofilm reactors were used to compare the influence of brass and stainless-steel plumbing materials on lead leaching, opportunistic premise plumbing pathogen growth and biofilm development under stagnant conditions. After four weeks and ten weeks of stagnation, the microbial quality of water and biofilm was analysed using selective culture and flow cytometry with cell sorting to determine the ratios of live, dead and injured fractions. Previously described qPCR protocols were then used to enumerate these pathogens from sorted live and injured cell fractions to determine which species were able to survive in the low nutrient conditions and compare biofilm communities formed on each material. Stainless steel bioreactors were found to support greater accumulation of biofilm at both sampling points when compared to brass bioreactors. Concerningly, the concentration of lead in stainless steel bioreactors after ten weeks stagnation was approximately 130 times greater than current Australian drinking water guidelines, despite being marketed as a low-lead alternative. It is essential that the risks of microbial contamination are understood to ensure the regulatory solution to lead in brass does not create a public health problem worse than that it was introduced to solve.