Most plumbing codes and safety regulations set the maximum hot water temperature at 120°F for plumbing fixtures like sinks, showers, and bathtubs. This limit is based on guidelines from the American Society of Sanitary Engineering (ASSE) and the Consumer Product Safety Commission (CPSC) to prevent scalding injuries.
At 120°F, it takes about five minutes for a burn to occur. But as temperatures rise, the risk increases dramatically—at 140°F, a severe burn can happen in just five seconds. This is especially dangerous for young children, the elderly, and individuals with sensitive skin or mobility issues.
In multi-family properties with central water heating systems, the set temperature may be higher—typically between 130°F and 140°F—to prevent bacterial growth, such as Legionella, which thrives in stagnant warm water. However, to comply with safety standards, mixing valves or anti-scald devices must be installed to ensure water reaches residents at a safe 120°F or lower.
Property managers should routinely inspect water heaters and mixing valves to verify they are functioning correctly. If residents report fluctuating water temperatures or concerns about hot water safety, a professional plumber should assess the system to prevent risks.
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