The presence and growth of Legionella species in thermostatic shower mixer taps: an exploratory field study.

Legislation in the Netherlands requires routine analysis of drinking water samples for cultivable Legionella species from high-priority installations. A field study was conducted to investigate the presence of Legionella species in thermostatic shower mixer taps. Water samples and the interior of ten thermostatic shower mixer taps were investigated for cultivable Legionella species. In seven cases, Legionella species was found in at least one of the samples. In four cases, Legionella species was detected in the biofilm on the thermostatic shower mixer taps interior, with the highest values on rubber parts, and in five cases in the cold supply water. These results show that thermostatic shower mixer taps can play a role in exceeding the threshold limit for cultivable Legionella species, but the cold supply water can also be responsible.Practical implications: This study showed that contamination of thermostatic shower mixer taps (TSMTs) with Legionella spp. was frequently observed in combination with conta...