Why stored hot water is kept hot and the delivered temperature is limited separately, and what that means for a vulnerable bather.
Hot-water hygiene and scald protection need coordinated controls. Reducing the entire store to lukewarm is not a substitute for limiting the temperature delivered to a vulnerable person.
Temperature as a hygiene control
Where temperature is the control regime, hot water is normally stored at 60 °C or above and distributed so it reaches 50 °C within one minute at the relevant check point; healthcare guidance uses 55 °C. These are hot-water hygiene checks, not a requirement to deliver that temperature from a thermostatically mixed bath or shower.
At a mixing valve, check the hot supply upstream as the monitoring procedure requires. The mixed outlet is checked separately against its safe-use limit. The thermostat dial does not tell you the actual temperatures, and temperature control also depends on circulation, turnover, maintenance and avoiding stagnant pipework. Follow the system’s documented hygiene regime and manufacturer instructions.
Prevent scalding at use
Hot water above 44 °C presents a serious scalding risk for vulnerable people during whole-body immersion. A person who cannot react or leave the bath quickly may need a lower limit and help with bathing. The appropriate assessment considers the person, temperature and exposure time; 44 °C is not safe in every case.
Fit and commission a suitable thermostatic mixing valve where needed, verify its actual delivered temperature and test the specified response to cold-supply failure. Continue the required hygiene regime upstream. A pressure-reducing valve controls pressure, and a manual mixer can still allow an excessively hot setting; neither gives thermostatic scald protection.