Legionella bacteria grow in water systems held between 20 °C and 45 °C, in stagnant pipework and in tanks with sediment. Hotels have all three risk factors: long pipe runs, rooms that sit empty, and storage tanks. The law expects duty holders to manage that risk — and to prove it.
The legal framework
- Health and Safety at Work etc. Act 1974 and COSHH 2002 set the duty.
- ACoP L8 (Approved Code of Practice) tells you how to comply; it has special legal status.
- HSG274 Part 2 covers hot and cold water systems in detail — temperatures, frequencies, flushing.
The duty holder (usually the operator or landlord) must appoint a competent responsible person, assess the risk, put a written scheme of control in place, and keep records for at least five years.
The monitoring regime
| Task | Frequency | | --- | --- | | Sentinel outlet hot/cold temperatures | Monthly | | Calorifier flow and return temperatures | Monthly | | Cold water tank temperature and condition | Six-monthly | | Showerhead and hose descaling and disinfection | Quarterly | | Flushing of infrequently used outlets | Weekly | | Thermostatic mixing valve (TMV) servicing | Annually | | Risk assessment review | Two-yearly or on change |
Tank chlorination and when it is needed
Chlorination (disinfection) of cold water storage tanks and downstream pipework is required after tank cleaning, after works that may have introduced contamination, and before reopening a building that has been closed. It is a standard step at the end of hotel refurbishments — we chlorinated the tanks before handover on the Premier Inn Epsom South Christmas project so the hotel reopened compliant.
Common gaps we find
- Risk assessment out of date after a refurbishment changed the pipework.
- Monitoring done but not recorded, or recorded on paper that cannot be found.
- Dead legs left after bathroom refits.
- Calorifiers below 60 °C because the set-point was lowered to save energy.
- No flushing log for unlet rooms during quiet periods.
Making compliance visible
Monthly temperature readings only protect you if they are recorded, trended and acted on. Our engineers record readings in the AiMS engineer app against each sentinel outlet; out-of-range results raise a task automatically and the audit pack exports in one click. See how this fits into our planned maintenance and compliance service or the PPM guide.
Frequently asked questions
- How often does a legionella risk assessment need to be reviewed?
- ACoP L8 requires review whenever there is reason to suspect it is no longer valid — a change to the water system, its use or key personnel, or a case of legionellosis. In practice most duty holders review every two years and after any significant refurbishment or period of low occupancy.
- What temperatures should hot and cold water reach?
- Hot water should be stored at 60 °C or above and reach 50 °C at outlets within one minute (55 °C in healthcare). Cold water should be below 20 °C within two minutes of running. Sentinel outlets are checked monthly.
- Do hotel bedrooms need flushing if they are empty?
- Yes. Outlets not used for a week should be flushed to prevent stagnation. During low occupancy, hotels should run a documented flushing regime for unlet rooms.