True or False: Three key factors in the design and selection of water heaters and mixing valves regarding Legionella control are stagnation, temperature, and surface area.

The statement is indeed true because stagnation, temperature, and surface area are critical factors in effectively controlling Legionella growth in water systems.

Stagnation refers to situations where water sits idle in plumbing systems or water heaters. When water remains stationary for extended periods, it provides an ideal environment for Legionella bacteria to proliferate. Thus, proper design must minimize stagnation by ensuring adequate flow rates and avoiding low-demand areas where water can sit.

Temperature is another crucial factor. Legionella bacteria thrive within a specific temperature range, particularly in warm water between 77°F and 113°F (25°C and 45°C). Water heaters should be set to supply hotter water (ideally above 140°F or 60°C) to help reduce the risk of bacterial growth. Additionally, cold water systems should maintain temperatures low enough to inhibit growth as well.

Surface area also plays a role in Legionella control, as larger surface areas can provide more opportunities for biofilm development, which can harbor bacteria. When selecting water heaters and mixing valves, consideration of materials and designs that minimize surface area and maximize cleanability is important to reduce the risk of legionellosis.

Overall, by addressing stagnation, maintaining appropriate temperatures, and minimizing favorable surface areas, the design