AC maintenance in Abu Dhabi: cooling systems, water hygiene and the Legionella Code

Updated 16 October 2026. Every rule in this guide links to its official source at the end of the page.

Key facts

• The Code: ADOSH-SF Code of Practice CoP 12.0, Prevention and Control of Legionnaires' Disease, Version 4.0 dated 15 July 2024, applies to all duty holders in the Emirate of Abu Dhabi.
• Which equipment: anything that uses, stores or disseminates warm water, including cooling towers, large air conditioning systems, hot water tanks, swimming pools, spas, fountains, emergency showers and fire sprinkler systems.
• Which buildings: single-family residential buildings are excluded; multi-tenanted residential buildings are treated as commercial, with the building or facility management company as duty holder.
• Risk assessment: duty holders must perform an annual health risk assessment and, where risks are found, implement a water treatment and maintenance programme.
• Sampling: by a competent person to standards approved by ESMA, such as BS 7592:2008, with samples tested by a laboratory certified by ESMA or the Abu Dhabi Quality and Conformity Council.
• Records: procedures, the maintenance and disinfection schedule, employee training records and records of confirmed cases or positive results.

Why AC in Abu Dhabi is also a water-safety issue

Most owners think of air conditioning as comfort and electricity bills. In Abu Dhabi, cooling plant is also covered by a public health Code, because many cooling systems hold warm water and produce fine droplets: cooling towers, evaporative condensers and the water systems around chillers. The Code targets exactly these conditions: equipment that produces water droplets, aerosols, mists and steam, and systems where water can stagnate.

The Abu Dhabi Occupational Safety and Health System Framework (ADOSH-SF) addresses this in its Code of Practice CoP 12.0, Prevention and Control of Legionnaires' Disease, Version 4.0, dated 15 July 2024 and published on the Abu Dhabi Public Health Centre's website. The Code applies to all duty holders in the emirate, is designed to incorporate requirements set by UAE and Abu Dhabi regulatory authorities, and states that where its requirements conflict with another authority's, employers must follow the more stringent requirement.

This page explains what the Code asks of building owners, management companies and employers, and how it fits with ordinary AC maintenance. The wider Abu Dhabi picture is in the Abu Dhabi maintenance guide, and drinking water tanks have their own guide: water tank cleaning in Abu Dhabi.

Who the Code applies to

CoP 12.0 applies to all duty holders and places of business in the Emirate of Abu Dhabi that have equipment that uses, stores or disseminates warm water. Its list includes, but is not limited to:

Two scope rules matter for property owners. Single-family residential buildings are not subject to the Code. Multi-tenanted residential buildings are considered commercial establishments, and the building management or facility management company is the duty holder and must follow the Code as if it were the building owner. So a villa owner with split units is outside its scope, while a residential tower with a central cooling plant, a pool and water features is inside it.

The Code also reminds duty holders to identify and follow all the legal requirements that apply to their operation or premises, in line with the Code.

The annual health risk assessment

The Code's first duty for building owners and management entities is an annual health risk assessment, to determine whether the building has any equipment or facilities that use or store water that is, or could become, contaminated with Legionnaires' disease bacteria, in accordance with ADOSH-SF Element 2 on risk management. If the assessment identifies such locations, the owner must implement a water treatment and maintenance programme to reduce the risk of bacterial growth. The Code points to ASHRAE Guideline 12-2000, Minimizing the Risk of Legionellosis Associated with Building Water Systems, for examples of acceptable programmes.

Employers have a parallel duty: assess their worksite for locations where the bacteria could be present, and for each one, develop a maintenance schedule and control measures to prevent growth.

In practice, a useful assessment, offered here as guidance, does four things:

1. lists every water-using system in the building, from cooling towers and chilled water plant to water heaters, showers, pools and water features;
2. identifies where water can stagnate, warm up or form droplets, such as cooling tower basins, little-used outlets, dead legs in pipework and decorative fountains;
3. rates the risk for each, considering who could be exposed, for example residents, guests, staff, patients or the public;
4. sets the controls, the frequency of each task and the person responsible, which becomes the maintenance programme.

Systems that need a maintenance programme

The Code requires duty holders and employers to develop maintenance programmes to prevent the growth of Legionnaires' disease bacteria for equipment and facilities that use and store water. Its examples are:

This list is the backbone of a building's water hygiene plan, and it reaches well beyond the AC plant room. For maintenance teams, it means the same programme that services the cooling tower also needs to cover the water heater outflow, the shower in an unused guest room and the decorative fountain in the lobby.

Cooling towers and evaporative condensers

The Code lists four points in cooling towers and evaporative condensers that need a maintenance programme: the make-up water, the basin, the sump, and the heat sources and chillers. It also requires equipment that produces water droplets, aerosols, mists and steam to be cleaned and disinfected regularly. A cooling tower does exactly that by design, which is why it sits at the centre of most building risk assessments.

A typical programme, offered here as guidance and to be set by the risk assessment and a competent water treatment specialist, covers:

Beyond safety, a clean, well-treated tower is also an efficient one: scale and biofilm on heat exchange surfaces make chillers work harder for the same cooling. Power Zone provides HVAC preventive maintenance and HVAC inspections and energy assessments.

Cleaning, disinfection and flushing

The Code's disinfection and control section contains three requirements that apply far beyond the cooling tower:

• employers and duty holders shall regularly clean and disinfect equipment and facilities that produce water droplets, aerosols, mists and steam;
• they shall establish a programme to regularly flush systems that are not in daily use, such as emergency eyewash and water storage tanks, to prevent water stagnating and bacteria growing;
• they are encouraged to follow ASHRAE Guideline 12-2000 when developing their prevention programmes.

The flushing requirement is the one most often missed. Hotels with unoccupied rooms, offices with closed floors, villas in compounds left empty in summer, emergency showers in plant rooms and sprinkler systems after use all hold water that can stagnate. A simple flushing log, room by room or outlet by outlet, is the most practical way to show it is being done.

Monitoring, inspection and sampling

The Code requires facility owners and employers to establish a monitoring and inspection programme, based on their risk assessment, to evaluate the effectiveness of maintenance and disinfection. When sampling for Legionnaires' disease bacteria is carried out, the Code requires that:

Monitoring is more than sampling. Routine readings of water treatment levels, temperatures at water heater outflows and outlets, visual checks of basins and drain pans, and a record of each flushing round all show whether the programme is working, long before a laboratory result does.

If a case is suspected or confirmed

The Code sets clear duties when illness is suspected:

• if an employee, building resident or other person is found to have a suspected or confirmed case of Legionnaires' disease or Pontiac fever, the duty holder shall have samples taken from any potential exposure site and analysed by a laboratory certified by ESMA or the Abu Dhabi Quality and Conformity Council;
• when the bacteria are found in a workplace, or an employee is confirmed to have the disease, the employer shall report the case immediately to both the Abu Dhabi Public Health Centre and the Department of Health, Abu Dhabi, to coordinate the response;
• employees shall report plant and equipment issues that could contribute to bacterial growth, and all suspected cases, to their employer.

For building managers, preparation means knowing in advance which competent person will take samples, which certified laboratory will test them, and where the building's water hygiene records are kept, so the response can start the same day.

Training for maintenance staff

The Code requires training to comply with ADOSH-SF Element 5 on training, awareness and competency, and Mechanism 7.0 on practitioner and service provider registration. Employees who maintain equipment that uses or stores water, or who work at or near it, must receive annual training from duty holders covering:

1. an explanation of Legionnaires' disease and its history;
2. its signs and symptoms;
3. sources of exposure and transmission;
4. risk factors;
5. precautions when working with potential sources;
6. strategies to prevent the growth of the bacteria.

When maintenance is outsourced, ask the provider how its technicians are trained on these topics and how that training is recorded; it is part of the evidence a duty holder may need to show.

Records the Code requires

At a minimum, the Code requires the following to be documented for Legionnaires' disease prevention programmes:

In practice, a single water hygiene file for the building, holding the annual risk assessment, the programme, the schedule, service reports, flushing logs, treatment readings, sampling results and training records, makes the system easy to manage and to demonstrate.

Split units, fan coils and condensate hygiene

Split units, ducted units and fan coil units do not hold warm water the way a cooling tower does, but they do produce condensate, and neglected drain pans, coils and ducts become wet, dirty surfaces inside the airflow. Even in villas, which are outside the Code's scope, condensate hygiene is part of good AC maintenance. The table below is guidance:

Power Zone provides AC servicing and component cleaning, duct cleaning and antimicrobial treatment and air filter supply and replacement.

Chilled water and central plant buildings

In buildings cooled by chilled water, from their own chillers or from a central plant, the water is delivered to fan coil units in each apartment or office. Responsibility is usually split: the plant and risers belong to the building or the cooling provider, while the fan coil, its valves, filters and drain belong to the unit. The checklist below is guidance for both sides:

• Fan coil units: clean filters and coils, clear condensate drains and pans, and check fan motors and controls;
• Valves and actuators: check that control valves open and close correctly so rooms cool as set and water is not wasted;
• Insulation: repair damaged insulation on chilled water pipes, which otherwise sweats, drips and stains ceilings;
• Plant rooms: pumps, strainers, expansion tanks and water treatment for the closed loop checked on schedule;
• Risers and ceiling voids: inspect for leaks and condensation before they damage finishes.

Power Zone provides pipe insulation and fan coil and HVAC maintenance.

Hot water, showers and little-used outlets

The Code lists water heater tanks at their inflows and outflows, faucets and showers among the potable water locations that need a maintenance programme, and requires systems not in daily use to be flushed. For buildings in scope, and as good practice in any building, that means:

• water heaters kept in good condition, with sediment removed where the design allows and temperatures set as the maintenance programme specifies;
• shower heads and tap aerators descaled and cleaned periodically;
• outlets in unoccupied rooms or floors run on a flushing schedule, with a log;
• dead legs left after renovations removed, so water does not stand in capped pipes;
• emergency showers and eyewash stations flushed regularly.

Power Zone provides water heater maintenance and plumbing fixture repairs; pools and spas are covered by pool maintenance.

Pools, spas and water features

The Code names swimming pools, hot tubs, heated spas, whirlpools, decorative fountains, waterfalls and water features among the equipment it covers and the locations that need a maintenance programme. In hotels, compounds and residential towers, these are often maintained by different contractors from the AC plant, but they belong in the same water hygiene programme. The points below are guidance:

• Circulation: keep water moving; a fountain switched off for weeks with water left in its basin is a stagnation risk.
• Treatment: maintain disinfection and water balance in pools and spas, with readings recorded at the frequency the programme sets.
• Cleaning: clean basins, nozzles and filters of features that create spray, because the Code requires regular cleaning and disinfection of equipment that produces droplets, aerosols or mist.
• Spas and hot tubs: warm water and spray together make them high-priority items in the risk assessment.
• Out of season: drain, clean and dry features that will be idle, or keep them treated and circulating, rather than leaving them half full.

Power Zone provides pool cleaning, water balancing and equipment maintenance, seasonal pool servicing and sauna and ice bath maintenance.

Emergency showers, eyewash stations and fire sprinklers

The Code lists emergency water systems, including safety showers, eye wash stations and fire sprinkler systems, within its scope, and names emergency eyewash and showers, and fire sprinkler systems after use, among the locations that need a maintenance programme. It also gives emergency eyewash as an example of a system not in daily use that must be flushed regularly.

These systems are built to be used rarely, which is exactly why water stands in them. A practical routine, offered as guidance, is to flush and inspect emergency showers and eyewash stations on a fixed schedule, record each flush, and, after any sprinkler discharge or system drain-down, include the sprinkler system in the building's water hygiene follow-up. Fire system testing itself remains a fire safety matter for the building's fire contractor; Power Zone's firefighting system maintenance covers it.

Irrigation, misting systems and humidifiers

The Code includes irrigation equipment among its other sources, and humidifiers and nebulisers, including bubblers for oxygen and water used for respiratory therapy equipment, among the locations that need a programme. Its requirement to clean and disinfect equipment that produces droplets, aerosols and mists regularly applies directly to outdoor misting fans and spray systems, which are common on terraces, majlis areas and outdoor seating.

Higher-risk occupants: hotels, hospitals, clinics and care homes

Risk assessments weigh who could be exposed as well as the equipment. Buildings that house older people, patients or large numbers of guests deserve a more careful programme, and the Code's inclusion of respiratory therapy water shows that healthcare settings are clearly in view. Practical steps, offered as guidance, include tighter flushing schedules for guest rooms and wards that are not occupied every day, priority attention to spas and water features in hotels, and a clear plan with the facility's infection control team for sampling and response. In every case, the Code's reporting duty applies: confirmed cases in a workplace are reported immediately to the Abu Dhabi Public Health Centre and the Department of Health, Abu Dhabi.

Choosing a provider for AC and water hygiene

The Code gives duty holders a set of questions to ask any provider involved in cooling plant and water systems:

For most buildings, the maintenance contractor, the water treatment specialist and the sampling company are different organisations working to one programme. Keeping them coordinated, with one file and one schedule, is the building manager's main task.

Incoming mains, softeners and storage

The Code's first group of locations needing a maintenance programme is the potable water system itself: the incoming water main, water softeners, holding tanks and cisterns, and water heater tanks at their inflows and outflows. These are where water enters the building and where it can sit. In practice, as guidance:

• Holding tanks and cisterns: cleaned, disinfected and inspected under the Regulation and Supervision Bureau's tank Code, explained in our Abu Dhabi water tank cleaning guide, with lids sealed and vents screened.
• Water softeners: serviced on schedule, with resin and brine tanks kept clean, because a neglected softener can become a place where water stands and deposits build.
• Water heaters: inflows and outflows included in monitoring, sediment removed where the design allows, and temperatures kept as the programme specifies.
• Pipework: dead legs removed and insulation kept on cold pipes so they do not warm up in ceiling voids.

Power Zone provides water tank cleaning, water filtration and softener maintenance and pump maintenance.

Bringing systems back after shutdowns and renovations

The riskiest moment for a building's water and cooling systems is often the restart: after a summer closure, a long vacancy, a refurbishment or a cooling tower shutdown. The Code's requirements to flush systems not in daily use, and to clean and disinfect equipment producing droplets and mist, apply directly. A restart checklist, offered as guidance, typically covers:

For renovations, add one more step: check that new pipework has not left dead legs or capped branches, and that new fan coils and drains are connected with a proper fall and trap. Power Zone's MEP snagging inspections include these checks before handover.

Who does what in a typical building

The Code assigns duties to three groups: duty holders, meaning facility or building owners and management entities; employers; and employees. In a typical multi-tenanted building, the split looks like this, offered as guidance on how the Code's roles map to day-to-day work:

Clear lines like these avoid the most common failure: everyone assumes someone else is flushing the empty floor, checking the cooling tower readings or keeping the records.

A year-round AC and water hygiene calendar

The calendar below is guidance for a commercial or multi-tenanted building; the risk assessment and programme set the actual frequencies.

How Power Zone maintains AC in Abu Dhabi

Power Zone maintains split, ducted, fan coil and central AC systems across the Emirate of Abu Dhabi with its own teams, part of 20 in-house teams covering all seven emirates. For commercial and multi-tenanted buildings, planned maintenance can be organised around the building's water hygiene programme: condensate and drain pan cleaning, coil and duct cleaning, filters, insulation, water heaters and flushing logs, with reports for the building file. Each job starts with a survey and an itemised quotation. See air conditioning, heating and ventilation services, how every job runs or request a site survey.

Frequently asked questions

Which Abu Dhabi Code covers Legionella in cooling systems?

ADOSH-SF Code of Practice CoP 12.0, Prevention and Control of Legionnaires' Disease, Version 4.0 dated 15 July 2024, which applies to all duty holders in the Emirate of Abu Dhabi.

Does the Legionella Code apply to my villa?

No. The Code says single-family residential buildings are not subject to it. Good AC maintenance still matters for comfort, efficiency and hygiene.

Does it apply to residential towers?

Yes. Multi-tenanted residential buildings are considered commercial establishments, and the building or facility management company is the duty holder.

What equipment does the Code cover?

Equipment that uses, stores or disseminates warm water, including cooling towers, large AC systems, hot water tanks, pools, spas, fountains, emergency showers, eyewash stations and fire sprinkler systems.

How often must the risk assessment be done?

Duty holders must perform a health risk assessment annually, and implement a water treatment and maintenance programme where risks are identified.

Which parts of a cooling tower need a maintenance programme?

The Code lists the make-up water, the basin, the sump, and the heat sources and chillers.

Do unused showers and taps need attention?

Yes. The Code requires a programme to regularly flush systems not in daily use, such as emergency eyewash and water storage tanks, to prevent stagnation.

Who can take Legionella samples in Abu Dhabi?

A competent person with training or experience in Legionella sampling, following ESMA-approved standards such as BS 7592:2008, with samples tested by a laboratory certified by ESMA or the Abu Dhabi Quality and Conformity Council.

Who must be told about a confirmed case?

The employer must report immediately to both the Abu Dhabi Public Health Centre and the Department of Health, Abu Dhabi.

What training must maintenance staff receive?

Annual training on the disease and its history, signs and symptoms, sources and transmission, risk factors, precautions near potential sources, and prevention strategies.

What records does the Code require?

Prevention procedures, the maintenance and disinfection schedule, employee training records, and records of confirmed cases or positive sampling results.

Why does my AC unit smell musty?

Usually a dirty drain pan, a blocked condensate line, or a dirty coil or filter. Cleaning the pan, clearing the drain and cleaning the coil normally solves it.

Who maintains fan coil units in a chilled water building?

Usually the unit owner or tenant maintains the fan coil, its filters, valves and drain, while the building or cooling provider maintains the plant and risers; check your building rules or lease.

Do misting fans fall under the Legionella Code?

The Code requires equipment that produces water droplets, aerosols and mists to be cleaned and disinfected regularly, which covers misting systems in buildings within its scope.

Do emergency showers need flushing?

Yes. The Code names emergency eyewash as an example of a system not in daily use that must be flushed regularly to prevent stagnation.

Are pools and spas covered by the Code?

Yes. Swimming pools, hot tubs, heated spas, whirlpools and water features are listed within its scope.

What should be done before reopening a building after summer?

Clean, disinfect and refill cooling towers with treatment restarted, flush all taps and showers, bring water heaters to temperature, clean AC filters, coils and drain pans, and record the restart.

Are water softeners part of the Legionella programme?

Yes. The Code lists water softeners, together with the incoming main, holding tanks and water heater tanks, among potable water locations needing a maintenance programme.

Who is the duty holder under the Legionella Code?

Facility or building owners and management entities. In multi-tenanted residential buildings, the building or facility management company is the duty holder.

Does Power Zone maintain AC in Abu Dhabi?

Yes. Power Zone's own teams maintain split, ducted, fan coil and central systems across the emirate, including condensate, coil, duct and water heater work that supports a building's water hygiene programme.

Sources

1. Abu Dhabi Public Health Centre, ADOSH-SF Code of Practice CoP 12.0, Prevention and Control of Legionnaires Disease, Version 4.0 (15 July 2024)
2. Abu Dhabi Public Health Centre, Codes of Practice