Differences in Microbial Communities in Drinking Water from Conventional Electronic and Manual Taps in Dependence on Stagnation and Flushing Cycles

Abstract

Water taps can be a reservoir for microorganisms and pose a risk for contamination and infection. In this work, water samples from different common taps were examined to determine the influence of certain parameters on the microbial load of drinking water. Methods: Four different types of taps were installed along the same water pipe. Over a period of six months, water samples were taken at specific intervals and analyzed for their colony-forming units (CFU/mL) and for the presence of the water pathogens Pseudomonas aeruginosa and Legionella pneumophilia. Two different flushing configurations were investigated: Setup A: the same flush intervals for all taps once a day to determine differences based on type, size and mode of operation. Experimental setup B: different flush cycles for manual and electronic taps to investigate the effects of water stagnation in the tap and whether electronic taps with automatic flushes improve water quality. Results: No Legionella pneumophilia and Pseudomonas aeruginosa were found during the study period. The size of the tap has a great influence on the number of CFU/mL—a maximum of 330 CFU/mL was found in the smallest tap and 1080 CFU/mL in the largest tap, with a significant difference. Stagnation in the tap leads to a significantly higher number of CFU/mL. The results of this work can be used as a basis for the development of innovative taps. There are many possibilities in terms of materials, tap size and intelligent action algorithms—such as automatic flushing—to maintain the quality of our drinking water in a resource-saving way.