The effect of a self-regulating trace heating element on Legionella within a shower
Related Experiment Video
Updated: Oct 13, 2026

Legionella pneumophila Outer Membrane Vesicles: Isolation and Analysis of Their Pro-inflammatory Potential on Macrophages
Published on: February 22, 2017
Abstract:
A self-regulating trace heating element was assessed for its ability to maintain a temperature of 50 degrees C in the mixer valve and dead-legs of a shower, and for its effect on legionellas colonizing the shower. The trace heating element maintained a temperature of 50 degrees C +/- 1.5 degrees C in dead-legs when the circulating hot water supply remained above 45 degrees C. Legionellas appeared in a trace heated dead-leg when the temperature of the dead-leg reached 45 degrees C and the hot water supply dropped below this temperature. Legionellas were eradicated or significantly reduced in sections of the shower where a temperature of 50 degrees C was consistently achieved. The mixer valve which was trace heated but not insulated remained colonized with Legionellas. Legionellas were found in shower water throughout the study.
Related Concept Videos
Physical Methods for Controlling Microbial Growth: Temperature
Hyperthermophilic Bacteria

