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Legionella · Food and beverage plants · Utilities and water
Key facts
- Foodborne? No. It is breathed in or aspirated (WHO, CDC)
- Legal status Risk Group 2 agent, HBA Regulations 2022
- Evaporative condensers controlled exactly like cooling towers
- Open systems Legionella sampling at least quarterly
- More than 1 000 cfu/L in cooling water: immediate action
- Idle more than a few days dose and circulate at least weekly
- Eyewash and emergency showers flush at least every six months
- Training before exposure, refresher every year or as the health and safety committee or representative recommends
For the manager who carries the Legionella duty on a food site
Legionella Responsible Person Training is built for the engineering, utilities, QA or SHEQ manager who carries this duty: the asset register, risk ratings, monitoring, and how to challenge a water treatment contractor’s report. Ten hours online, R2 950.
Is Legionella a foodborne pathogen?
No. The WHO and the CDC describe two routes of infection: breathing in small droplets of water that carry the bacteria, and aspiration, where contaminated water goes down the wrong way into the lungs. Water that goes into the stomach normally is not the route, and neither is food. Legionnaires’ disease is a severe pneumonia, not a gut infection.
That changes where it sits in your system. Unlike Listeria monocytogenes or Salmonella, it is no threat to the person who eats your yoghurt, so in practice it does not belong in the product HACCP plan. It is a hazard to the people who breathe the spray your plant makes: operators, cleaners, refrigeration technicians, contractors, canteen staff and neighbours. It belongs in your occupational health and safety risk assessment and in the utilities part of your prerequisite programme.
The law agrees. R638, the hygiene regulations for food premises, requires potable water that complies with SANS 241, but sets no water temperatures and does not mention Legionella. The duty comes from the OHS Act (sections 8 and 9) and the Regulations for Hazardous Biological Agents, 2022, which list Legionella spp. as a Risk Group 2 agent. Our guide to Legionella regulations in South Africa sets out every duty.
Where does Legionella grow in a food or beverage plant?
Legionella becomes a risk when four things line up: the bacteria are present, the water sits between about 20 and 45 °C, biofilm, scale or sludge give it food and shelter, and there is a way out to people as breathable droplets. A food plant has all four, mostly in utilities nobody from QA walks past.
| System | Why it carries risk | What control looks like |
|---|---|---|
| Evaporative condensers on ammonia refrigeration | Warm water recirculates over the coil and drift leaves on the wind | Written treatment scheme, dip slides weekly, Legionella at least quarterly, intact drift eliminators |
| Process cooling towers | The same as a condenser, plus fouling from process leaks | As above, plus a clean whenever fouling is known or suspected |
| High-pressure washdown and crate washing | Turns whatever is in the supply into mist at head height. Assessed as other plant that creates spray | A controlled supply, bystanders kept out of the mist |
| Reused and recovered water | Stored, possibly warm, then sprayed | Assessed as a water system in its own right |
| Food misting, tunnel pasteurisers, effluent treatment | All named as risk systems in HSE HSG274 Part 3 | On the asset register with cleaning and checks |
| Change room showers | Geysers set low, showers idle over shutdowns | Hot water stored at 60 °C or above, idle showers flushed weekly |
| Emergency eyewash and showers | Stagnant water delivered straight into the face | Flushed to drain at least every six months, heads cleaned quarterly |
What does a Legionella walk-through find at a dairy?
In our courses we use Amanzi Dairy, a training scenario built from real audit patterns rather than a real business: a milk, yoghurt and maas plant with 220 staff on two shifts. Most South African food sites I walk have some version of its problems.
- Evaporative condensers 25 metres upwind of the canteen’s fresh air intake. Their drift heads for the air the canteen breathes. HSE’s 2024 guidance says towers should ideally not be sited near ventilation inlets. Moving them is rarely practical, so the controls must be excellent.
- A Legionella sample “once a year before the customer audit”. HSE asks for sampling at least quarterly on evaporative cooling. One sample timed for the auditor proves the system was clean on one day.
- Pasteuriser cooling water reused for crate washing through a high-pressure cleaner that throws a visible mist. The recovered water is mains water used once through the pasteuriser’s water-cooling section, separate from the cooling tower circuit, but it is still stored, possibly warm water, sprayed at head height.
- Change room showers on a 500 litre geyser set at 50 °C. Stored hot water should be 60 °C or above. The WHO notes that L. pneumophila can withstand 50 °C for several hours. See our hot water temperature guide.
- Eyewash and emergency showers never flushed since installation, in the chemical store and the ammonia plant room. The first person splashed gets stagnant water in the eyes.
- A three-week shutdown every December. The raw milk intake is diverted to another processor, and the plant, its refrigeration included, stands still for three weeks in mid-summer.
- Nobody appointed. The engineering manager, Mr Pillay, “looks after Legionella” with no written appointment and no training. The contractor works on purchase orders with no written agreement, and the health and safety committee has never discussed Legionella.
A fair walk-through also records what is right: the CIP hot water tank runs at 75 °C, well above the growth range, and dip slides are done weekly.
Free tool: rate your own plant’s water systems
The free Legionella Risk Assessment and Water Management Plan Builder has a food and beverage plant setting. List your condensers, towers, washdown and showers, rate them, set limits and corrective actions, and export a spreadsheet.
The builder gives you the form. Legionella Responsible Person Training (R2 950) teaches the judgement behind every rating and limit.
Can reused water be used for washdown?
Water reuse saves water and money, and I support it. Before recovered water goes anywhere it can become spray, the risk assessment should answer five questions:
- What temperature does it sit at? Between 20 and 45 °C it is in the growth range.
- How long does it stand, including weekends and the shutdown?
- Is the tank covered, cleanable and actually cleaned?
- Is it disinfected, and is the level checked where the water is used?
- Where does it become spray, and who is standing in it?
The answer is not necessarily to stop reusing. Put the reuse tank on the asset register with a control limit, a check and an owner, and stop turning uncontrolled water into mist. The product safety side is in ASC’s article on water reuse in food production.
Your crate wash operator works inside the mist
Legionella Awareness Training gives refrigeration technicians, utilities operators, cleaners and crate wash staff the four conditions, the temperature numbers, safe flushing and what to report, with a dairy as one of the cases. Four hours on a phone, R799 a person.
Are washdown, crate washers and misters a Legionella risk?
They can be. In Bogalusa, Louisiana, in 1989, an ultrasonic mist machine over a grocery store’s produce display caused 33 cases of Legionnaires’ disease and 2 deaths. People who had spent more than 30 minutes near the display were more likely to be cases. The CDC then advised dismantling and cleaning produce misters weekly with hypochlorite at 50 ppm or more.
A high-pressure cleaner is a mist maker with a lance, and the operator works inside the cloud. Feed it from a supply you control, drain hoses and lances after use rather than leaving water standing in a warm room, keep bystanders out of the mist, and give every spray-producing machine a named owner on the asset register.
What do FSSC 22000 and BRCGS auditors ask for on Legionella?
I will not quote clause numbers here. Auditors on GFSI-benchmarked schemes such as FSSC 22000 and BRCGS look at utilities and water as part of the prerequisite programme. When I audit a plant, the Legionella questions come out of that review, and the evidence I expect is built on what the HBA Regulations require, plus the good practice that proves it:
- A documented risk assessment by a competent person, reviewed at least every 24 months and after any change.
- A schematic and asset register of the water systems.
- The contractor’s written scheme, a signed agreement and service reports with real numbers.
- Results over time, and what was done about every result outside its limit.
- A written appointment and training records.
- A shutdown and restart procedure.
A single clean result with no trend behind it is weak evidence. For the documents themselves, see our Legionella risk assessment guide and water management plan template.
What should happen during the December shutdown?
- Cooling plant idle for more than a few days: dose with biocide and circulate at least weekly (HSG274 Part 1).
- Shut down for a month or more: clean and disinfect before restart. HSE allows a risk assessment to set a shorter period, and three weeks in summer is a good reason to.
- Before the first shift: flush showers, hose stations and eyewash stations and check hot water temperatures. Our flushing procedure guide has the steps and a log to copy.
Tower detail, from drift eliminators to action levels, is in our cooling towers and evaporative condensers guide.
Who on a food site needs Legionella training?
The HBA Regulations require training for employees who may be exposed, before possible exposure, with a refresher every year or at intervals the health and safety committee or representative recommends (regulation 4(4)). On a food site that means refrigeration technicians, utilities operators, crate wash and cleaning staff, and the artisans who flush and descale. The appointed manager needs more: the risk assessment, the plan, contractor oversight and reading results. See who is responsible for Legionella.
Getting it wrong is more than an audit finding. In South Africa, 98.8 percent of the Legionnaires’ disease cases notified from January 2018 to September 2020 were hospitalised (NICD). Under section 38(2) of the OHS Act, an employer who negligently causes an injury (conduct that would have been culpable homicide had the person died) faces a fine of up to R100 000 or two years’ imprisonment, or both.
What the Responsible Person course gives you
- An asset register and schematic method for every water system on site
- The ASC risk rating scale, practised on a complete risk assessment for a 140-room hotel
- A monitoring schedule and corrective action matrix
- A results reader and a contractor oversight checklist
- The plan builder, which exports your own plan as an xlsx workbook
- A dated certificate on passing. HPCSA CPD accredited
Stop relying on one sample a year
Run Legionella control on your utilities the way you run every other prerequisite programme: written, monitored and verified. Self-paced, on a phone, no classroom day.
Frequently asked questions
Is Legionella a foodborne pathogen?
No. Legionella infects people when they breathe in contaminated droplets or when water is aspirated into the lungs, according to the WHO and the CDC. Eating food or swallowing water normally is not the route. In a food plant it threatens the workers, contractors and neighbours who breathe the spray, not consumers.
Does a food factory need a Legionella risk assessment?
Yes, where its water systems make spray that people breathe. The HBA Regulations, 2022 list Legionella spp. as a Risk Group 2 agent and require a documented risk assessment by a competent person, reviewed at least every 24 months. Condensers, cooling towers, washdown, reused water, showers and eyewash stations all belong in it.
Do FSSC 22000 and BRCGS audits cover Legionella?
Not directly. The schemes deal with food safety, and Legionella is an occupational and public health hazard. Auditors on GFSI-benchmarked schemes look at utilities, water and legal compliance, so a Legionella risk assessment and its records are what they may ask to see. The contractor’s records and a trend of results show that part is controlled. The legal duty itself comes from the OHS Act and the HBA Regulations, 2022, not from the certification scheme.
How often should evaporative condensers be tested for Legionella?
At least quarterly, by a laboratory accredited for the method, with dip slides weekly and operational checks daily, following HSE guidance for evaporative cooling. One sample a year before an audit does not show control. A result above 1 000 cfu/L calls for immediate action and a resample within 48 hours.
Can recovered or reused water be used for washdown?
Yes, if the reuse system is managed as a water system in its own right: a known temperature, a covered and cleaned tank, disinfection checked at the point of use, and no uncontrolled water turned into mist where people breathe it. Put the reuse tank on your asset register.
What should happen to cooling plant during a shutdown?
If it stands idle for more than a few days, dose it with biocide and circulate at least weekly. After a shutdown of a month or more, clean and disinfect before restart, or sooner if your risk assessment says so. Flush showers, hose stations and eyewash stations before the first shift.
Who should manage Legionella on a food site?
A named, competent person appointed in writing, usually the engineering, utilities, QA or SHEQ manager. The chief executive can assign the duty under section 16(2) of the OHS Act but stays responsible. That person needs training beyond awareness: the risk assessment, the water management plan, contractor oversight and reading results.
Put your plant’s utilities on a written plan before the next audit
Ten hours for the manager who signs off the plan and the contractor. Four hours for the people who work in the spray. Both built on South African law and South African plants.
Enrol in the Responsible Person course (R2 950) →Awareness Training for your team (R799)Self-paced, works on a phone. HPCSA CPD accredited. Certificate on passing.
Sources and further reading
- WHO fact sheet: legionellosis
- CDC: about Legionnaires’ disease
- HSE HSG274 Part 1: evaporative cooling systems (2024)
- HSE HSG274 Part 3: other risk systems
- CDC MMWR (1990): the Bogalusa produce mister outbreak
- Regulations for Hazardous Biological Agents, 2022
- R638 of 2018: hygiene requirements for food premises
- NICD Public Health Bulletin (2020): notified Legionnaires’ disease
- Occupational Health and Safety Act 85 of 1993