What the rules require, in full
Both documents are published by Dubai Municipality and both are current: GU44 is at version 6 (issued 19 August 2025, superseding 17 December 2024); GU17-DW2 is at version 1. Where they overlap, they agree.
| Requirement | How often | Source |
|---|---|---|
| Tanks emptied, cleaned and disinfected with 50 mg/l chlorine | At least twice a year | GU44 V6 · GU17 §8-3(a)6 |
| Tanks kept clean and inspected internally, coverings intact and firmly in place | At least monthly | GU44 V6 · GU17 §8-3(a)7 |
| Visual inspection of tanks and outlets for dirt, organic matter and build-up | At least weekly | GU17 §8-3(a)12 |
| Whole system flushed — water at ≥70 °C for 5 minutes, or chlorine at 1–2 mg/l free residual at all outlets | Every six months | GU44 V6 |
| Water heaters (calorifiers) kept clean, drained and disinfected | At least twice a year | GU44 V6 · GU17 §8-3(a)9 |
| Cold water kept below 20 °C throughout the system, at every outlet | At all times | GU44 V6 · GU17 §8-3(a)3 |
| Hot water circulating at 50–60 °C; storage at a minimum of 60 °C | At all times | GU17 §8-3(a)2 |
| Taps and showers in unoccupied rooms flushed | Weekly, and before occupation | GU17 §8-3(a)1 |
| Daily records of temperature, pH, chlorine and biocide readings, checked by the manager | Daily | GU44 V6 |
| A named, trained person responsible for water safety in the building | Standing duty | GU17 §8-3(a)11 |
| Laboratory sampling by an EIAC-accredited laboratory | At least every six months | GU17 |
The gap a cleaning certificate does not cover
A cleaning certificate proves the tank was clean on the day of the visit. Read the table again and count what it does not prove: the monthly internal inspection, the weekly visual check, the daily readings — and above all the requirement that cold water stays below 20 °C at every outlet, at all times.
That last line is not a target. It is the boundary of the growth band. Dubai Municipality’s own guideline lists the conditions favouring legionella as a temperature range of 20–45 °C. A Dubai rooftop tank in July sits inside that band for hours a day. Between two cleanings — 182 days apart — nothing in a certificate says whether it did.
So the honest question for a building owner is not “when was the tank last cleaned?” It is: how many hours a day does our water spend between 20 and 45 °C? A cleaning certificate cannot answer it. A six-monthly laboratory sample is a snapshot, not a record. Only a continuous temperature record can.
That is the gap continuous legionella monitoring for Dubai buildings closes: sensors in the tank, on the calorifier flow and return, and on cold-water risers record around the clock, and every reading is sealed at the moment it is taken. When an inspector, an insurer or a tenant asks how you know the water is safe today, you show a complete record — not last quarter’s certificate.
Honest scope. Neither GU44 nor GU17 mandates sensors or continuous monitoring — the words do not appear in either document. What they mandate is a temperature regime held at all times and daily records of it. Continuous monitoring is how that regime is evidenced. It is not itself a legal requirement, and we will not tell you otherwise.
Your water tank compliance checklist
- Cleaning and disinfection records — dated, from a company approved by Dubai Municipality’s Food Safety Department, certificate valid, before/after documentation retained
- Monthly internal inspection — coverings intact and firmly in place, no cracks, no daylight entering, insect screens sound
- Weekly visual check — sediment, biofilm and organic matter in tanks and at points of use
- Cold water below 20 °C at every outlet, verified continuously — the hardest line to hold in a Dubai summer and the most commonly breached
- Hot water at 50–60 °C circulating, 60 °C in storage
- Dead legs and low-use outlets — removed, disconnected or flushed weekly (vacant units are the classic blind spot)
- Daily readings of temperature and chlorine, signed off by a manager
- Six-monthly system flush at ≥70 °C for 5 minutes, or chlorination to 1–2 mg/l at all outlets
- A named, trained person responsible for water safety — if “who owns water safety in this building?” has no answer, that is your first gap
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↓ Download the checklistWhere this sits alongside the rest of your water compliance
Tank cleaning is one line in a larger regime. GU44 covers storage tanks, calorifiers, cooling towers, fountains, water features, spas and irrigation storage — the scope is defined by equipment, not by industry. If your building also has a swimming pool, the pool chemistry regime runs in parallel: see the pool compliance module. For hotels, the water, pool, air and vape obligations arrive together — the hotel bundle sets out the combined load.
Primary sources
Every requirement on this page comes from a Dubai Municipality guideline, on DM’s own site. Read them yourself — we would rather you check us than take our word for it.
- DM-HSD-GU44-LCWS2 — Technical Guidelines (44) for Controlling Legionella in Water Systems, V6, issued 19 August 2025
- DM-HSD-GU17-DW2 — Technical Guidelines (17) for Quality of Un-bottled Drinking Water, V1 — Section 8-3, Operational Measures
FAQ
How often should water tanks be cleaned in Dubai?
At least twice a year. Dubai Municipality's Technical Guidelines for Legionella Control in Water Systems (DM-HSD-GU44-LCWS2, V6, issued 19 August 2025) require all water storage tanks, water heaters and water filters to be emptied, cleaned and disinfected at least twice a year, and immediately if legionella is detected. Cleaning uses chlorine at 50 mg/l. Treat it as a minimum, not a target.
Who is allowed to clean a building's water tanks in Dubai?
A company approved by Dubai Municipality's Food Safety Department. The guidelines also require the company to follow DM-approved cleaning and disinfection methods, to produce reports listing the chemicals and methods used, and to keep training records for its workers. The cleaning and disinfection certificate must be valid, and the reports kept with your building records.
Is a cleaning certificate enough to prove the water is safe?
It proves the tank was clean on the day of cleaning. It does not evidence the monthly internal inspection, the weekly visual check, the daily temperature and chlorine readings, or the requirement that cold water stays below 20 °C at all outlets at all times — all of which the same Dubai Municipality guidelines require.
What water temperatures does Dubai require in buildings?
Cold water below 20 °C throughout the system at all outlets, at all times; hot water circulating at 50–60 °C with storage at a minimum of 60 °C. Legionella favours the 20–45 °C band, which is exactly what the temperature regime is designed to avoid.
How often must building water be tested in a laboratory?
Drinking water samples at least once every six months, taken by a laboratory accredited by EIAC. Samples are also required about a week after each routine cleaning and disinfection, and after any emergency disinfection.
Is continuous monitoring legally required in Dubai?
No. Neither guideline mandates sensors or continuous monitoring — the words do not appear in either document. What they mandate is a temperature regime held at all times and daily records of it. Continuous monitoring is how that regime is evidenced; it is not itself a legal requirement.