Temperature Monitoring
Watch: Step-by-Step Demo
Purpose
To check hot and cold water temperatures at taps to prove the water is safe from Legionella.
Required Equipment
Calibrated digital thermometer, probe wipes, monitoring sheets or tablet
Required PPE
Gloves for hot water. Heat-resistant gloves if touching pipes.
Required Tools
Digital probe thermometer (calibrated), clipboard or tablet, site tap list
Step-by-Step Method
- Find the taps you need to check (use the site list). These are usually sentinel taps - the first and last on each pipe loop.
- Start with the nearest hot tap. Run it and measure the temperature after 1 minute.
- Write down: 50 degrees C or above = PASS, below 50 = FAIL.
- Go to the furthest hot tap. Run and measure after 1 minute. Write it down.
- Check the nearest cold tap. Run and measure after 2 minutes. 20 degrees C or below = PASS.
- Check the furthest cold tap. Run and measure after 2 minutes.
- Check the hot water cylinder flow temperature (60 degrees C or above needed).
- Check the hot water cylinder return temperature (50 degrees C or above needed, 55 in hospitals).
- If checking all taps (yearly), go through each one.
- Write down all results with date, time, tap name, temperature, and pass/fail.
- Tell someone about any failures so they can be fixed.
Pass Criteria
Hot water 50 degrees C or above within 1 minute (55 in hospitals). Cold water 20 degrees C or below within 2 minutes. Cylinder flow 60 degrees C or above. Return 50 degrees C or above (55 in hospitals).
Fail Criteria
Hot water below 50 degrees C after 1 minute. Cold water above 20 degrees C after 2 minutes. Cylinder flow below 60 degrees C. Return below 50 degrees C (55 in hospitals).
Common Problems & Corrections
Hot water below 50 degrees C - Check cylinder thermostat, circulation pump, mixer valve, and return temperatures. Check for dead legs. Cold water above 20 degrees C - Check tank location and insulation, pipes near hot pipes, and circulation. Sometimes passes, sometimes fails - Check timer settings, mixer valve drift, or system balancing.
Warnings
Hot water at cylinder temperature (over 60 degrees C) can scald. Do not touch pipes at the cylinder. Use gloves when testing hot water.
Relevant Legislation
ACOP L8 (4th Edition), HSG274 Part 2, HTM04-01 (healthcare)