Legionella risk assessments and water hygiene, with the records to prove it

A legionella risk assessment is a written assessment of a building’s hot and cold water systems that finds where legionella bacteria could grow and sets out how to control them, as required by the HSE’s Approved Code of Practice L8. Rossair’s water hygiene team carries out the assessment and then runs the controls it calls for: monthly temperature monitoring, legionella testing where it is needed, TMV servicing, tank inspection and cleaning, and flushing of little-used outlets. Every check is logged in one compliance pack.

Book a legionella risk assessment
01420 566822
What we deliver

Risk assessment, monitoring and remedials for commercial and public-sector buildings

If you employ people or control a building, you have a legal duty to prevent or control the risk of legionella in its water systems. That covers offices, schools and colleges, care homes, hospitals, hotels, retail units and industrial sites. Our engineers survey the system, assess the risk and write the scheme to control it. They then carry out the monthly checks, the servicing and the remedial work that scheme requires, so the assessment does not sit in a folder while the water systems drift. Findings, readings and actions are recorded as they happen, signed and dated.

  • Legionella risk assessment to L8 and HSG274, with a schematic of the water system and a prioritised action list
  • Written scheme and on-site log book setting out what is checked, how often and by whom
  • Monthly temperature monitoring at sentinel outlets, with calorifier flow and return checks
  • Legionella sampling and testing where the risk assessment calls for it
  • TMV servicing, with strainers and filters cleaned and descaled
  • Cold water tank inspection, cleaning and disinfection
  • Flushing regimes for little-used outlets, and showerhead and hose cleaning
  • Remedial work, then updated records for audits and insurers
Commercial plant room with pressure vessels, water treatment and ductwork
In detail

How we control legionella, topic by topic

The figures and frequencies below come from the HSE’s technical guidance, HSG274 Part 2. Your risk assessment can set tighter ones for your building, and we write that into the scheme.

Legionella risk assessment (L8)

Duty holders must assess the risk under the Health and Safety at Work etc Act 1974 and COSHH, and L8 explains how. Our engineer surveys the hot and cold water systems, draws the schematic, identifies tanks, calorifiers, TMVs, dead legs and little-used outlets, and records the significant findings with a prioritised action list. The assessment is reviewed when the system or the use of the building changes, or when monitoring shows the controls are not working.

Written scheme and monthly monitoring

The written scheme sets out how the system is run and checked. HSG274 expects temperatures at sentinel outlets every month: hot water at 50°C or more within one minute of running (55°C in healthcare premises) and cold water below 20°C within two minutes. Calorifier flow is set as close to 60°C as practicable and never below it, with returns not below 50°C. Readings are logged with the engineer’s name and the date.

Legionella testing and sampling

HSG274 does not ask for routine sampling of every system. Testing is used where the risk assessment calls for it: where temperature or disinfectant controls are not being met, in higher-risk buildings such as healthcare, and after a suspected case. Samples are taken to BS 7592 and analysed in a UKAS-accredited laboratory. Above 100 cfu/l the system is resampled and the controls reviewed; above 1,000 cfu/l the review is immediate and disinfection is considered.

TMV servicing

Thermostatic mixing valves blend hot and cold water, typically to between 38°C and 46°C, to guard against scalding. The blended water downstream can also support legionella, so HSG274 expects regular routine maintenance by competent people to the manufacturer’s instructions, with strainers and filters inspected, cleaned, descaled and disinfected annually or as the risk assessment sets. We service each valve, check that Type 3 valves fail safe if the cold supply is interrupted, and log the result.

Water tank inspection and cleaning

HSG274 expects an annual inspection of every cold water storage tank, inside and out: a closely fitted lid, intact insect screens on overflows and vents, sound insulation and a clean water surface. Where the inspection shows contamination or faults, we clean and disinfect the tank and rectify the defects. Debris or signs of vermin mean the tank is inspected more often. Cleaning, flushing and disinfection to BS 8558 is also carried out after refurbishment or work that opens the system.

Flushing and remedial work

Outlets not used for seven days or more go on a flushing regime. HSG274 gives weekly flushing for several minutes as the usual routine for infrequently used outlets, and says it must be sustained and logged because lapses can cause a critical rise in legionella. Showerheads and hoses are cleaned and descaled quarterly or as fouling requires. Remedials include removing dead legs, repairing tanks and insulation, replacing TMVs and cleaning and disinfecting the system.

In schools and colleges

Schools and colleges carry the same duty, with extra pressure points: pupil washrooms and early years TMVs, showers and changing rooms, and outlets left unused through the holidays. Our school water hygiene page covers flushing around the school year and the records a school needs for its compliance file.

Water hygiene for schools and colleges

Water hygiene scheduled with the rest of the estate

1973
UK building services contractor since
20+
Years at Chichester College Group
11
Campuses under one PPM contract
L8
HSE Approved Code of Practice we work to

Legionella control only works if the monthly checks actually happen. We put water hygiene on the same PPM schedule as the rest of your plant, scheduled to SFG20, so the readings, tank inspections and TMV services are booked and chased alongside heating, ventilation and electrical testing. At Chichester College Group, whose estate we have maintained for over 20 years across 11 campuses under one PPM contract, Legionella Risk Assessment (LRA) compliance is part of that contract. Contract clients also have 24/7 emergency cover if a result or a failed system needs action out of hours.

Compliance

What legionella control is assessed against

  • L8HSE Approved Code of Practice (4th edition, 2013): risk assessment, a competent person, a control scheme and its review.
  • HSG274 Part 2HSE technical guidance on controlling legionella in hot and cold water systems: temperatures, monitoring, flushing, TMVs, tanks and sampling.
  • HSWA and COSHHHealth and Safety at Work etc Act 1974 and the COSHH Regulations 2002 put the duty on employers and those in control of premises.
  • BS 7592Code of practice for sampling for legionella bacteria in water systems.
  • BS 8558Cleaning, flushing and disinfection of hot and cold water services, for example after refurbishment or a long period out of use.
  • RecordsSignificant findings recorded where there are five or more employees. Monitoring and inspection records are kept for at least five years.
5 sectors

Sectors we serve

EducationFlushing around school holidays, TMVs in pupil washrooms and a complete compliance fileCareLegionella control for vulnerable residents, with records ready for inspectionNHS HealthcareWater safety in healthcare premises, where HSG274 sets higher hot water temperaturesCommercialOffice and retail risk assessments, monthly checks and tank cleaningFacilities ManagementWater hygiene scheduled and reported across a whole portfolio
Related pages

Water hygiene alongside the rest of your maintenance

Water hygiene for schools and collegesHoliday flushing, pupil washroom TMVs and records for the school compliance file.PPM contractsMonthly water checks on the same SFG20 schedule as heating, ventilation and electrical testing.Commercial maintenance servicesReactive and planned maintenance with 24/7 emergency cover for contract clients.
Frequently asked

Questions about legionella risk assessments and water hygiene

What is a legionella risk assessment?
A legionella risk assessment is a written assessment of the water systems in a building. It identifies where legionella bacteria could grow, such as stagnant outlets, warm cold water, cool hot water, tanks and dead legs, who could be exposed, and what must be done to control the risk. It results in a written scheme for managing the system and a record of the significant findings.
Is a legionella risk assessment a legal requirement, and who needs one?
Yes. Employers and those in control of premises must assess and control the risk of legionella under the Health and Safety at Work etc Act 1974 and the COSHH Regulations. That includes landlords and managing agents of commercial buildings. HSE says simple, low-risk domestic-type systems do not need an in-depth assessment. A commercial building with tanks, calorifiers, TMVs or many outlets is a more complex system, and the duty holder must either understand it or appoint a competent person who does. Where there are five or more employees the significant findings must be recorded.
What is an L8 risk assessment?
L8 is the HSE’s Approved Code of Practice, Legionnaires’ disease: the control of legionella bacteria in water systems (4th edition, 2013). An L8 risk assessment is a legionella risk assessment carried out to that code. It gives legal status to five areas: risk assessment, the competent person, the control scheme, review of the control measures, and the duties of those who supply water systems. HSE’s technical guidance, HSG274, sets out the practical detail.
How often does a legionella risk assessment need reviewing?
The law sets no fixed interval. The assessment must be reviewed regularly and whenever there is reason to think it is no longer valid, for example after a change to the water system or the use of the building, if checks show controls are failing, if key personnel change, or after a case of Legionnaires’ disease linked to the system. We record a review date in the report. Records must be kept for as long as they stay current and at least two years afterwards, and monitoring and inspection records for at least five years.
Do I need legionella testing?
Not for every system. HSG274 says sampling is appropriate where the risk assessment calls for it: where temperature or disinfectant levels are not being consistently met, where a building has more susceptible occupants such as in healthcare, and where a case or outbreak is suspected. Samples are taken to BS 7592 and analysed in a UKAS-accredited laboratory. A result above 100 cfu/l triggers resampling and a review of the controls, and above 1,000 cfu/l an immediate review and possible disinfection.
What temperatures should hot and cold water be kept at?
Under HSG274, hot water is stored at 60°C or above and should reach 50°C within one minute at the outlet (55°C in healthcare premises), with circulating returns not below 50°C. Cold water should be below 20°C within two minutes of running a sentinel tap. Growth is more likely when cold water is above 20°C, hot water is below 50°C or water sits unused. We check sentinel outlets monthly and log every reading.
How often do TMVs and water tanks need servicing?
Cold water storage tanks should be inspected at least annually, more often if debris or vermin are found, and cleaned and disinfected where the inspection shows it is needed. HSG274 sets no single interval for TMVs: they need routine maintenance by competent people to the manufacturer’s instructions, with strainers and filters cleaned, descaled and disinfected annually or as your risk assessment sets. We agree the schedule for each valve and tank in the written scheme and add it to your PPM calendar.

If we’re not the right fit, we’ll tell you who is

Book a legionella risk assessment

Your enquiry goes to our technical team. We call back within one working day.

We’ll only use your details to respond to your enquiry. See our privacy notice.

Call 01420 566822