Legionella risk assessment for Warehouses and distribution centres
Updated 12 September 2026
Key points
- A legionella risk assessment is required for warehouses and distribution centres premises under the Health and Safety at Work Act 1974 and the Approved Code of Practice L8
- Typical cost: £250 to £700
- 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
A warehouse can be the simplest water system in commercial property, or a deceptively awkward one. The floor itself may have almost no outlets, but the welfare block — toilets, canteen, locker-room showers for drivers — is often plumbed in at one end of a very large building. That means hot water travels a long way to reach few outlets, which produces exactly the long, slow pipe runs where temperature is lost and water sits in the growth range. Shower rooms used hard at peak season and barely at all in quiet months are a recurring finding.
The building fabric adds to the problem. Cold pipework running through an unheated, uninsulated roof space warms up in summer and can sit for weeks in the 20 to 45°C band where legionella multiplies. Cold water storage tanks in roof voids are common in older units and are often out of sight and out of mind. Where the site has vehicle wash-down, a water-fed dock leveller system, or any evaporative cooling in the ventilation plant, each is a separate water system needing its own controls.
On multi-let trading estates there needs to be a clear line between the landlord's duty for common parts and risers and each tenant's duty inside their own unit, mirroring the arrangement in multi-tenanted offices. Both sides should hold their own assessment. Seasonal agency staffing is worth recording in the assessment too, because a welfare block sized and managed for thirty permanent staff behaves very differently when two hundred temporary workers arrive for the Christmas peak.
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 warehouses and distribution centres 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 warehouses and distribution centres 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 warehouses and distribution centres 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 warehouses and distribution centres 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 warehouses and distribution centres premises typically costs between £250 and £700, 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.