PREVRA Thermometer Calibration Using Boiling Water: Verify Your Probe Accuracy in Under Two Minutes
A step-by-step visual guide to the boiling water calibration method. Required under HACCP — your temperature records are only as reliable as the thermometer that took them.
Why thermometer calibration is a critical HACCP requirement
An uncalibrated thermometer is worse than no thermometer at all. It gives you false confidence. Under HACCP, if you are monitoring a Critical Control Point with a thermometer — and you almost certainly are — that thermometer must be calibrated and the calibration must be recorded. An EHO will check both your thermometer and your calibration log.
A surprising fact: digital probe thermometers can drift by 1-2°C over a few months of daily use without any obvious sign of damage. In a busy kitchen, a 2°C error is the difference between food being legally safe and illegally unsafe. The boiling water method gives you a quick check at 100°C (adjusted for altitude — in most UK locations, water boils between 99.5°C and 100°C at sea level).
Calibrating your thermometers with the boiling water method
Display this poster near your probe thermometers. The method: bring a pan of water to a rolling boil, insert the probe into the water without touching the pan sides or base, wait for the reading to stabilise, and record the result. The reading should be 100°C (±0.5°C at UK altitudes). If it is off by more than 1°C, adjust if your model allows it or replace the thermometer. Calibrate every probe weekly and record every calibration.
Digital SFBB includes a calibration log where staff record results from any device. The system prompts when calibration is due and flags readings outside tolerance. Your EHO sees a complete calibration history for every thermometer in your kitchen.
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