Section 607.1/Hot Water Supply System Requirements
IPC 607 covers hot water supply system requirements including maximum temperature limits, thermostatic mixing valves, scald prevention, and hot water distribution system design.
The hot water supply system must deliver water at temperatures suitable for the intended use while preventing scalding injuries. Section 607.1 limits the maximum hot water temperature to fixtures to 120 degrees F for bidets, 110 degrees F for public hand washing, and 120 degrees F for bathtubs and whirlpool bathtubs. Water heaters are typically set to 140 degrees F to control Legionella bacteria, so thermostatic mixing valves (TMVs) or temperature-limiting devices must be installed to reduce the temperature at the fixture. Section 607.2 requires that the hot water supply system be designed to deliver hot water to fixtures within a reasonable time, which may require hot water recirculation systems or on-demand circulation pumps in large buildings. The cross-connection protection requirements apply to all hot water system components including mixing valves and recirculation loops.
Why this section exists
Scalding from excessively hot water is a leading cause of burn injuries in buildings, particularly affecting children, elderly residents, and people with disabilities who may have slower reaction times or reduced sensation. Water at 140 degrees F causes a third-degree burn in 5 seconds. At 120 degrees F, the exposure time increases to over 5 minutes. The temperature limits and TMV requirements balance two competing health risks: Legionella bacteria thrive in water between 77 and 113 degrees F (requiring storage above 140 degrees F), but water delivered to fixtures above 120 degrees F causes scald injuries. TMVs resolve this conflict by allowing high-temperature storage for pathogen control while delivering safe temperatures at the fixture.
What plan reviewers look for
Plan reviewers check the plumbing drawings for water heater setpoint temperature and thermostatic mixing valve locations. They verify TMVs are specified at or near fixtures where the code limits apply (bathtubs, showers, public lavatories). They check the hot water distribution system for pipe sizing and recirculation provisions in large buildings. They verify the water heater T&P relief valve discharge is piped to a safe location. For buildings with vulnerable populations (healthcare, assisted living, childcare), they may require point-of-use TMVs rather than a single central mixing valve.