Legionella is the bacterium behind Legionnaires' disease, and in the UAE the conditions it likes are part of everyday building life: hot roofs, stored water, long pipe runs and busy hotel and restaurant kitchens. If you manage a food outlet, hotel, gym or office in Dubai, Abu Dhabi or Sharjah, this guide explains how Legionella gets into a building's water, what Dubai Municipality's technical guideline expects, what a risk assessment should cover, and the routine that keeps it under control.
TL;DR
- Legionella grows in water between 20°C and 50°C, according to the WHO. In UAE heat, the cold side of the system is the hard part to keep below 20°C.
- Dubai Municipality publishes a technical guideline on Legionella control in water systems (DM-HSD-GU44). It expects a risk assessment, hot water stored at 60°C and delivered at 50°C or more, and cold water below 20°C.
- Rooftop tanks, warm ceiling voids, fit-out dead legs and idle outlets are the usual problem areas.
- Spray taps, showers, ice machines and cooling plant are how contaminated droplets reach people.
- UV disinfection helps at the supply or point of use, but only alongside temperature control and flushing.
Need a Legionella risk assessment for your site? Talk to Our Team about your premises and the equipment you run.
In this article
- How Legionella gets into a UAE building
- What Dubai Municipality's guideline expects
- What a Legionella risk assessment covers
- The UAE problem areas, outlet by outlet
- A monthly and yearly routine
- Biocide options and UV
- Frequently asked questions
- Sources
How Legionella gets into a UAE building
Legionella lives naturally at low levels in fresh water. It becomes a hazard when a building gives it three things: warmth, still water and something to grow on, such as scale, sediment or biofilm. The World Health Organization says the bacteria grow at 20°C to 50°C, with an optimum around 35°C, and that people are usually infected by breathing in contaminated aerosols, not by drinking water (WHO).
In a temperate country, cold mains water often arrives below 20°C and stays there. In the Emirates it frequently does not. Most UAE buildings store water in rooftop or basement tanks before use, and between May and October a tank on a sunlit roof, or a cold pipe crossing a hot ceiling void, can warm well into the growth range. So the question for a UAE operator is not only "is the hot water hot enough?" but "can we keep the cold water cold?"
"The bacteria live and grow in water systems at temperatures of 20 to 50 degrees Celsius (optimal 35 degrees Celsius)." Source: World Health Organization, Legionellosis fact sheet.
What Dubai Municipality's guideline expects
Dubai Municipality's Technical Guidelines for Legionella Control in Water Systems (DM-HSD-GU44) is the main local reference. In summary, it expects:
- a Legionella risk assessment of the water system
- hot water stored at 60°C or above, and reaching 50°C or more at the outlet
- cold water kept below 20°C
- the hot, warm and cold system flushed, cleaned and disinfected at least every six months
The guideline is written for Dubai. In Abu Dhabi, food businesses fall under the Abu Dhabi Agriculture and Food Safety Authority (ADAFSA), and the other emirates have their own municipal regimes. Wherever you are, check the current requirements for your premises with your licensing authority. International references such as the WHO guidance and ASHRAE Standard 188 follow the same approach: assess the system, control temperatures and stagnation, and keep records.
You will also see British documents quoted in UAE reports. The HSE's ACOP L8 and HSG274 are the benchmark in Great Britain, and BS 8580-1:2019 is the British Standard code of practice for how a Legionella risk assessment is carried out and written up. They are not UAE law, but they are useful when a local guideline is silent. Ask your assessor which documents their report is based on.
What a Legionella risk assessment covers
A risk assessment is a written survey of the whole water system, with a judgement on where Legionella could grow, how people could be exposed, and what needs to change. For a UAE site, a competent assessor will usually:
- Trace the supply from the incoming main to the storage tank, booster pumps, water heaters and every outlet.
- Read temperatures at the tank, the heater flow and return, and the nearest and furthest outlets on each circuit.
- Open the tanks to check lids, vent and overflow screens, insulation, sediment and signs of biofilm.
- Find still water, including capped branches from previous fit-outs and outlets that rarely run.
- List the spray sources: showers, pre-rinse spray taps, ice machines, glass washers, misting fans and cooling plant.
- Name who is at risk: guests, staff, cleaners and anyone more vulnerable, such as older visitors or patients.
- Write an action plan with owners, dates and a monitoring log.
The document is only useful if the routine behind it runs. Inspectors and insurers will usually ask to see the log, not just the report.
The UAE problem areas, outlet by outlet
| Part of the system | Why it is a risk in the UAE | What usually fixes it |
|---|---|---|
| Rooftop and basement tanks | Sun and plant-room heat warm the water, and large tanks turn over slowly | Shade, insulate, tight lids and screened vents, size to demand, inspect and clean |
| Cold pipes in ceiling voids and risers | Pick up heat from voids, hot pipes and kitchen extract | Insulate and separate from hot services, check temperature at the tap |
| Water heaters and calorifiers | Sludge at the base, or set too low to save energy | Store at 60°C, drain and inspect, balance return loops |
| Fit-out dead legs | Frequent tenant changes leave capped branches full of still water | Remove back to the main run during works |
| Idle outlets | Terraces, function rooms, staff showers and closed floors in summer | Weekly flushing, logged |
| Pre-rinse spray taps and showers | Create the fine mist that carries the bacteria | Descale and disinfect on a schedule |
| Ice machines and beverage lines | Hold water in warm kitchens and bars | Planned servicing, sanitising and inlet filter changes |
| Cooling towers and district cooling plant | Warm water plus drift | Specialist treatment by the plant owner or operator |
Summer is the pressure point for many Dubai venues. Terraces close, some floors go quiet, and water sits in pipes for days at exactly the temperatures Legionella likes. A summer flushing rota for closed areas, and a full flush and check before reopening in the cooler months, is one of the cheapest controls there is.
Ice machines need particular care because ice goes straight into drinks. Our guide to ice machine filtration in the UAE covers the inlet side, and our water dispenser maintenance guide covers sanitising and filter changes for drinking water points.
A monthly and yearly routine
The checking frequencies below follow the UK Health and Safety Executive's technical guidance (HSG274 Part 2), which is widely used as a reference in the Gulf. Your assessor may tighten them for UAE conditions.
Every week
- Flush outlets that are not used daily, including closed areas, and record it.
Every month
- Record hot water temperature at the heater flow and return.
- Record temperatures at sentinel outlets: hot should reach 50°C or more, cold should be below 20°C.
Every quarter
- Dismantle, descale and disinfect shower heads and spray heads.
Every six months
- Flush, clean and disinfect the hot, warm and cold system, as Dubai Municipality's guideline sets out.
Every year, or more often in summer conditions
- Inspect cold water tanks and clean where needed.
- Review the risk assessment, and always after a fit-out, a change of use or a failed check.
On the equipment schedule
- Service and sanitise ice machines, beverage systems and dispensers, and change filters on time.
If your cold water cannot be held below 20°C in July and August, the assessment should say so plainly and add compensating controls, such as more frequent flushing, better insulation or point-of-use treatment. Our maintenance plans can take on the equipment side of this schedule and keep the records.
Biocide options beyond temperature
Hot water at 60°C does a lot of the work, but keeping cold water below 20°C through a UAE summer is often out of reach. That is where biocides come in. HSG274 Part 2 splits them into two groups.
Treatments that travel through the pipework. These leave a residual that keeps working downstream:
- Chlorine, held at 0.5 to 1.0 mg/l free chlorine at outlets. Good at slowing new biofilm, weaker against old, established biofilm.
- Chlorine dioxide, held at 0.1 to 0.5 mg/l at outlets. Better at getting into biofilm, but it escapes as gas from hot water.
- Copper and silver ionisation, which releases metal ions from electrodes. It works in hot and cold circuits, but hard water scales the electrodes.
- Silver stabilised hydrogen peroxide, dosed into the supply to the maker's instructions.
Treatments that work at one point. Ozone and UV treat the water where the unit is fitted and leave nothing in the pipes after it.
Whichever you choose, the dosing equipment needs checking at least weekly and the residual needs measuring at sentinel outlets. Cooling towers and district cooling plant have their own specialist treatment, usually run by the plant operator.
Where UV disinfection fits
UV disinfection treats water as it passes a UV-C lamp, damaging the DNA of bacteria so they cannot multiply. It adds no chemicals and needs no contact tank, which suits hotels, healthcare sites and kitchens that want to avoid chemical handling. It leaves no residual in the pipework downstream, so it works alongside temperature control and flushing, never instead of them.
In a UAE building, UV usually sits on the supply after the storage tank, or at a single point of use such as a dispenser, ice machine feed or vending machine. Our SovSafe UV systems are built for this kind of installation. For the trade-offs against chlorine dosing, see UV disinfection vs chemical treatments.
UV lamps lose output with age and must be replaced on schedule, and the quartz sleeve must stay clean. Both fit on the same visit as your filter changes. Request a Quote with your flow rate and the outlets you want to protect.
How Sovereign Water helps
We work on the water treatment side of UAE food, hospitality and office sites: filtration, UV disinfection, scale control, and the dispensers, ice and beverage equipment that rely on the supply. We carry out Legionella risk assessments for UAE sites too: we trace the system, record temperatures, check tanks and outlets, and hand over a written report with an action plan you can show an inspector. We then recommend and install treatment suited to your water and trading pattern, and keep it serviced and documented.
Frequently asked questions
What is Legionella?
Legionella is a group of bacteria found naturally in fresh water. In building water systems it can multiply in warm, still water, and breathing in contaminated droplets can cause Legionnaires' disease, a serious form of pneumonia.
Is a Legionella risk assessment required in the UAE?
Dubai Municipality's technical guideline on Legionella control in water systems expects a risk assessment of the water system. Requirements vary by emirate and type of premises, so check the current position with your licensing authority.
What temperatures control Legionella?
Dubai Municipality's guideline expects hot water stored at 60°C or above and reaching at least 50°C at the outlet, with cold water below 20°C. The WHO says Legionella grows between 20°C and 50°C.
Why is cold water a problem in the UAE?
Stored water in rooftop tanks, and cold pipes running through hot ceiling voids, can warm past 20°C in summer. That puts the cold side of the system in the growth range unless tanks and pipes are shaded, insulated and kept moving.
Does UV disinfection remove Legionella?
UV inactivates bacteria in the water passing through the unit, but it leaves no residual in the pipes after it. It is one layer of control alongside temperature, flushing and tank management.
Talk to us about your site
Tell us where your premises are, how water is stored, and which equipment you run. We will suggest a practical next step for your site. Get in Touch.
Sources
- World Health Organization, Legionellosis fact sheet (growth at 20°C to 50°C, optimum 35°C, aerosol transmission, accessed 8 October 2026)
- Dubai Municipality, Technical Guidelines for Legionella Control in Water Systems, DM-HSD-GU44 (risk assessment, hot and cold water temperatures, six-monthly flushing and disinfection)
- UK Health and Safety Executive, HSG274 Part 2, Legionnaires' disease technical guidance (PDF) (checking frequencies and biocide target levels)
- British Standards Institution, BS 8580-1:2019 Water quality. Risk assessments for Legionella control. Code of practice
- ASHRAE, Standard 188, Legionellosis: Risk Management for Building Water Systems
