Cooling tower maintenance in Dubai is governed by Dubai Municipality's technical guideline for Legionella control in water systems. Its current version, V6, was issued on 19 August 2025 under reference DM-HSD-GU44-LCWS2. The guideline requires automatic biocide dosing, drift eliminators, regular testing and cleaning of the whole cooling system at least every six months. Those rules exist because cooling towers can spread Legionella bacteria through drift.
Cooling towers are often treated as simple HVAC plant, but they are also a public health risk. This guide explains why Dubai Municipality regulates them and what the guideline requires. It covers testing limits, action levels and the routine cleaning cycle. It also explains the records building owners and facility managers should keep for inspections.
Why does Dubai Municipality regulate cooling towers?
Dubai Municipality regulates cooling towers because they can grow Legionella bacteria and release them in drift. Warm water, sediment, biofilm and stagnation create good conditions for the bacteria to multiply. People who inhale contaminated aerosol can develop Legionnaires' disease, a potentially fatal pneumonia.
The Dubai Municipality guideline notes that cooling towers and evaporative condensers are among the best documented outbreak sources. It therefore treats the whole cooling water system as one unit, including tanks, pumps, pipes and filters. That scope matters, because cleaning the tower alone leaves other parts contaminated.
Quick Answer
Dubai Municipality regulates cooling towers because they can grow Legionella and spread it through drift aerosol. The guideline covers the whole cooling water system, including tanks, pumps, pipes and filters.
What does the Dubai Municipality guideline require for cooling towers?
Cooling towers and make-up water tanks need automatic biocide dosing that works all year. Towers need drift eliminators and must direct drift away from air intakes, windows and entrances. The whole cooling water system must be emptied, cleaned and disinfected at least every six months.
A competent person must inspect the water treatment system at least monthly and test total bacteria count monthly. A system shut down for more than four days must be cleaned before restarting. Premises must also keep a Legionella risk assessment current and reviewed after changes.
Quick Answer
Dubai Municipality requires automatic biocide dosing, drift eliminators and six-monthly emptying, cleaning and disinfection of the cooling water system. Monthly inspections by a competent person and bacteria tests are required.
What are the Legionella limits for cooling towers in Dubai?
The guideline sets a limit for cooling water systems of no more than 1,000 colony forming units of Legionella per litre. The aerobic bacterial count must not exceed 10,000 colony forming units per millilitre. Results above these limits trigger clearly defined corrective actions.
Where Legionella exceeds 1,000 units per litre, emergency decontamination including tower shutdown is required, whatever the aerobic count. An immediate cleaning and disinfection must follow, with resampling and a review of dosing and risk controls. Lower exceedances require dosing checks, resampling and cleaning if the result repeats.
Quick Answer
Cooling water in Dubai must stay at or below 1,000 cfu per litre of Legionella and 10,000 cfu per millilitre aerobic count. Serious exceedances require shutdown, cleaning and immediate disinfection.
How often should cooling tower water be sampled?
The guideline's sampling table sets minimum quarterly samples, at least every three months, for regulated systems. For cooling towers, it lists one sample from each make-up water tank and each collection basin. Monthly total bacteria counts and daily disinfectant readings add routine monitoring between those samples.
Samples should be taken by trained staff and analysed by an EIAC-accredited laboratory, with chain-of-custody records kept. The guideline also includes a daily log sheet for recording disinfectant levels in each tower. Our chiller AMC guide explains how routine readings reveal plant problems early.
Quick Answer
Dubai Municipality's guideline requires quarterly samples from each cooling tower make-up tank and each collection basin. Monthly bacteria counts and daily disinfectant readings provide routine monitoring between those quarterly samples.
What should a cooling tower maintenance contract cover?
A cooling tower maintenance contract should cover water treatment, dosing checks, sampling, six-monthly cleaning and disinfection, and mechanical servicing. Mechanical work includes fans, motors, belts, bearings, drift eliminators, fill, nozzles and basin condition. The contract should state who is the competent person responsible for monthly checks.
It should also define response times for failed samples and emergency disinfection. Dubai Municipality must approve the water system maintenance company, so check that before signing. Many owners combine cooling tower work with their HVAC and chiller AMC to keep records in one place.
Quick Answer
A cooling tower contract should cover water treatment, sampling, six-monthly cleaning, mechanical servicing and emergency disinfection response. Dubai Municipality requires water system cleaning and maintenance companies to hold its approval.
Frequently Asked Questions
How often must cooling towers be cleaned in Dubai?
What is the Legionella limit for cooling towers in Dubai?
What happens if Legionella exceeds the limit?
Do cooling towers need drift eliminators in Dubai?
Who can maintain cooling towers in Dubai?
What is a Legionella risk assessment?
What records should be kept for cooling towers?
What should happen after a long shutdown?
How is a cooling tower disinfected in an emergency?
Is cooling tower maintenance part of an HVAC AMC?
Main Takeaways
Dubai Municipality's guideline DM-HSD-GU44-LCWS2, version 6 of August 2025, governs cooling tower Legionella control in Dubai. It requires automatic biocide dosing, drift eliminators and six-monthly cleaning and disinfection of the whole system. Legionella must stay at or below 1,000 cfu per litre of cooling water. Quarterly sampling, monthly checks, daily logs and approved contractors keep cooling towers compliant and safe.
Keeping cooling towers compliant
Cooling towers keep Dubai buildings cool, but they need public health controls as well as routine mechanical care. Dubai Municipality's guideline turns those controls into clear, checkable routines for dosing, testing, cleaning, disinfection and recordkeeping. Following them carefully protects occupants, neighbours, passers-by and the building's reputation. Missing them can force emergency shutdowns of the tower during peak summer cooling demand.
Start by checking when your cooling water system was last fully emptied, cleaned and disinfected. Confirm that sampling results, daily disinfectant logs and your Legionella risk assessment are all current. QSERV maintains HVAC, chiller and cooling tower plant for commercial and hospitality buildings across the UAE. Contact us to review your cooling tower maintenance, water treatment programme and compliance records.
