Legionella Risks in Offices Every Manager Should Know
A facilities manager once told us the water system in her building, “had never given anyone any trouble.” That was true, right up until an environmental health visit asked for the risk assessment she didn’t have. There was no fine, but there were several weeks of scrambling to prove a system was safe that nobody had actually checked.
That’s the position most offices are in. Legionella risk is the ordinary consequence of water sitting somewhere warm, still, and unmonitored, and any office with a water system carries a legal duty to manage it. Meeting that duty rarely means a wholesale overhaul. A commercial Legionella risk assessment usually shows exactly where the risk sits and what, if anything, needs to change.
Here’s what every office manager needs to know before the next tenant asks.
Do Offices Need a Legionella Risk Assessment?
Yes, the Health and Safety Executive (HSE) sets out four conditions that create a foreseeable Legionella risk, and any system that meets them requires an assessment regardless of the building’s size. Water stored or recirculated in the system is the starting point.
Then three further factors decide whether that stored water is a genuine hazard:
A temperature between 20 and 45°C, warm enough for bacteria to grow.
Breathable droplets, from an outlet, shower head, or cooling tower.
A nutrient source such as rust, sludge, scale, or biofilm.
This surprises many office managers, who assume Legionella is a problem in hotels or care homes. The HSE names hot and cold-water systems as common sources in ordinary buildings too, alongside cooling towers and spa pools where present. An office kitchen tap used once a week, a rarely visited shower room, or an unused water tank in the plant room can all qualify [1].
All systems need an assessment, but not everyone needs elaborate control measures. The HSE is clear that a simple assessment can be sufficient where it shows the risk is properly managed. What matters is knowing where your water sits, moves, and stagnates, and documenting that so the record protects you if it’s ever questioned.
Who Is Responsible for Legionella Checks at Work?
Responsibility sits with the employer or whoever controls the premises, the duty holder in HSE terms. They must appoint a “competent person” to manage the risk, someone who has:
Sufficient authority to act on findings.
The competence to assess the system properly.
The right practical skills.
Working knowledge of the system itself.
Relevant experience.
That person doesn’t need to be a Legionella specialist. It can be the duty holder, a member of staff, or someone from outside the business.
Where several people share responsibility, such as across shift patterns or a multi-let building, everyone needs to know exactly what falls to them. If a contractor carries out water treatment, the duty holder stays accountable for the standard of that work, so it’s worth checking a contractor’s competence before hiring them. The HSE points to the service providers’ code of conduct and the British Standards Institute’s Legionella risk assessment standard as ways to do that [2].
Can You Carry Out Your Own Risk Assessment?
In principle, yes, provided whoever does it has the authority, competence, and time to do the job properly. In practice, most office managers are already stretched across enough responsibilities that bringing in a specialist is the more reliable option.
Is Legionella Testing a Legal Requirement & How Often
Assessing and controlling the risk is a legal requirement under the COSHH Regulations 2002, which classes Legionella as a biological agent. That means employers must assess the risk, control exposure, and train staff on the precautions in place. Testing itself isn’t automatically mandatory, but it’s usually how assessments are done in practice [3].
There’s no fixed legal interval for reviewing the assessment, but HSE is specific about what a good review checks. Its benchmark is that hot water outlets should reach at least 50°C, or 55°C in healthcare premises, within one minute of running [4].
Review against that whenever:
The water system changes in any way.
A new tenant moves into the building.
Part of the building goes unused for a period.
“We did one once” won’t hold up if circumstances have moved on. Keeping the assessment current is the point, not filing it away.
Where This Leaves You
Right now, most office managers are one tenant question or one inspection away from realising they can’t evidence their Legionella compliance. Once the duty holder is identified and a proper risk assessment is in place, that uncertainty disappears. Legionella control becomes a routine line item, with a documented record ready whenever anyone asks.
Asbury has carried out commercial water hygiene work across the South of England for more than 60 years, backed by Gas Safe and SafeContractor accreditation on every visit. Our engineers assess, document, and review Legionella risk for office buildings, so the duty holder ends up with a defensible record rather than a guess.
