Legionella risk assessment for Offices
Updated 16 August 2026
Key points
- A legionella risk assessment is required for offices premises under the Health and Safety at Work Act 1974 and the Approved Code of Practice L8
- Typical cost: £180 to £450
- Review every 12 months, or sooner if the water system, its use, or the people using it change
- A named duty holder (usually the employer, landlord, or building operator) must arrange it and act on its findings
Office water systems are usually simple: a mains cold feed to the kitchenettes and toilets, a small under-sink water heater or a single hot water cylinder, and that is often all. The risk is correspondingly modest, but it is not zero. Legionella thrives in stagnant, warm water, and offices routinely create exactly those conditions. Disabled toilets that see occasional use, showers in bike-commuter facilities that sit idle for weeks, kitchen taps in breakout areas used only at lunchtime, and little-used outlets in meeting room suites are all classic legionella traps.
The standard office legionella risk assessment looks at hot water storage temperatures, the distribution temperature at each outlet, any stored cold water, and the frequency of use across all outlets. Where an outlet is used less than once a week, it needs flushing on a scheduled basis, and someone needs to be tasked to actually do it. Open-plan offices that have been partly let after the pandemic are a common problem area because entire floors of plumbing may have been sitting unused for months.
In multi-tenanted buildings, there needs to be a clear line between the landlord's duty for the common parts and risers, and the tenant's duty for the water system inside their own demise. Both sides should have their own assessment, and the landlord should have an overarching one that covers the shared infrastructure.
Is it legally required?
Yes. The Health and Safety at Work Act 1974 places a general duty on employers and those in control of premises to protect people from health risks. The Approved Code of Practice L8 sets out how this duty applies specifically to legionella, and HSG274 provides the technical detail. These apply to offices premises with any water system that can aerosolise water, including taps, showers, spray humidifiers, fountains, and cooling towers.
Who is the duty holder?
The duty holder is whoever has control of the premises or the water system. For offices premises, this is usually the employer, owner, landlord, or managing agent. The duty cannot be contracted out: you can hire a water hygiene consultant, but the legal responsibility still sits with you.
If you are unsure who holds the duty for your premises, see: Who is responsible for a legionella risk assessment?
What the assessment should cover
ACOP L8 sets out five things a suitable and sufficient assessment must do:
- Identify and assess sources of risk across the whole water system, including stored hot and cold water, dead legs, rarely used outlets, and any equipment that generates aerosols
- Produce a written scheme for preventing or controlling the risk, with specific tasks, temperatures, and frequencies
- Implement, manage, and monitor the scheme in practice, not just on paper
- Keep records of the assessment, the scheme, monitoring results, and any remedial action taken
- Appoint a competent person (often called the "responsible person") to be accountable for the scheme
Free legionella risk assessment template
A structured Word document following the five-step approach in ACOP L8. Covers risk identification, written scheme, monitoring, and records. If it isn't written down, you can't evidence it.
Follows ACoP L8 and HSG274 Part 2. Free. No spam.
Specific water system risks to check
For offices premises, assessors typically pay close attention to:
- Hot water storage temperatures (calorifiers must reach 60°C throughout)
- Hot water distribution temperatures (50°C within one minute at outlets)
- Cold water storage tank condition, lid seal, and temperature (below 20°C)
- Dead legs, redundant pipework, and little-used outlets
- Shower heads, flexible hoses, and thermostatic mixing valves
- Any cooling tower, evaporative condenser, or spa pool (these are notifiable to the local authority under the Notification of Cooling Towers and Evaporative Condensers Regulations 1992)
How often to review
There is no fixed legal interval, but ACOP L8 requires that the assessment is reviewed regularly and whenever there is reason to believe it may no longer be valid. For most offices premises, that means at least every 12 months and sooner after any of the following:
- Changes to the water system (new pipework, fittings, equipment)
- Changes to the use of the building or the number of occupants
- A positive legionella test result or a case of Legionnaires' disease linked to the premises
- Prolonged periods of low occupancy or system shutdown (a risk during holidays, term breaks, or refurbishment)
- New guidance from HSE
Typical cost
A professional legionella risk assessment for offices premises typically costs between £180 and £450, depending on the size of the building, the number of water outlets, and whether there are any cooling towers or evaporative condensers (these add significantly to the cost because of the statutory inspection regime).
Use our cost calculator for an estimate based on your specific water system.
Need a legionella risk assessment for your premises? We will be partnering with Legionella Control Association registered providers shortly.
Free legionella risk assessment template
A structured Word document following the five-step approach in ACOP L8. Covers risk identification, written scheme, monitoring, and records. If it isn't written down, you can't evidence it.
Follows ACoP L8 and HSG274 Part 2. Free. No spam.