Gas Fitter Practice Test

What is the maximum safe temperature for potable hot water supply?

1. 120°F

2. 140°F

3. 160°F

4. 180°F

The correct answer is: 140°F

The maximum safe temperature for potable hot water supply is mainly set to prevent scalding and ensure user safety, particularly in residential settings. A temperature of 140°F is recognized as a balance between providing comfortable hot water while minimizing the risk of scalding. At this temperature, it takes longer for skin to receive burns compared to higher temperatures, thus offering a safer environment for users, especially children and the elderly who are more susceptible to hot water burns. Water temperature settings above 140°F pose a greater risk for severe burns. For instance, at 160°F, a burn can occur in seconds, which is why this temperature exceeds the safety limit for household hot water supply. Setting water heaters at this higher temperature is generally not recommended for domestic use, even though it may be suitable for commercial settings where sanitation standards might require such temperatures. The 120°F setting is often viewed as too low for effective disinfection, particularly in preventing Legionella bacteria growth. Therefore, while it is a safer option regarding burn risk, it may not sufficiently mitigate health risks associated with water temperature. In summary, 140°F represents the maximum safe temperature which effectively balances scald prevention while maintaining the bacterial control needed for a potable hot water supply in typical household applications.