Turn on a tap anywhere in Dubai and the water that comes out was, not long before, the sea. That is not a figure of speech. It is the literal supply chain, and it is one of the more remarkable pieces of infrastructure most residents never think about.
It is worth understanding properly, partly because it is genuinely interesting, and partly because knowing where the water comes from changes which questions about it are worth asking — and which ones are imported from somewhere else entirely.
A country with almost no fresh water
The UAE has no permanent rivers. Rainfall is minimal and irregular. There are groundwater reserves, but the great majority of them are too saline for drinking and are used mainly for irrigation. Nationally, only a small fraction of groundwater is classed as drinkable, and salt intrusion has been reducing that over time.
So the drinking water had to come from the only source available in quantity: the Arabian Gulf. In Dubai, roughly 98.8% of the water supply is desalinated seawater, with a little over 1% drawn from groundwater wells held largely as strategic and emergency reserve. Across the UAE as a whole, desalination supplies around 42% of total water demand — a share that looks smaller only because so much groundwater goes to agriculture — and the country accounts for a substantial slice of world desalination capacity.
How you turn the sea into drinking water
There are two families of method, and Dubai uses both.
Thermal distillation
The older approach, and for decades the dominant one here, is multi-stage flash distillation. In principle it is what a kettle does. Seawater is heated and passed through a series of chambers at progressively lower pressures, so at each stage a portion of it flashes instantly into vapour. That vapour is condensed back into fresh water, leaving the salt behind. It works reliably at enormous scale, and it pairs neatly with power stations, because the heat is a by-product you already have. DEWA has operated dozens of these units at its Jebel Ali complex.
It is also energy-hungry, which is why the balance has been shifting.
Reverse osmosis
The newer approach uses pressure rather than heat. Seawater is forced against a membrane with pores so fine that water molecules pass through and dissolved salts, for the most part, do not. No boiling, considerably less energy.
Dubai has moved decisively in this direction. The Hassyan plant — commissioned by DEWA with ACWA Power — is designed as the second-largest reverse osmosis desalination plant in the world and the largest anywhere powered by solar energy. It has a capacity of 818,000 cubic metres a day, enough for around two million people, and it is designed to run at about 2.9 kilowatt-hours per cubic metre, which is exceptionally efficient by the standards of the industry. It is coming online through 2026, with full capacity planned for 2027.
Whatever else you think about the water, that is a serious piece of engineering.
The water leaving the plant is very good
This is where a lot of water filter marketing quietly misleads people, so let us be direct.
DEWA reports that its water complies fully with World Health Organization drinking water guidelines and with the regional GSO 149 standard. Water is tested against more than a hundred parameters before it enters the distribution network — bacteria, heavy metals, pH, chemical contaminants — with continuous automated monitoring and thousands of samples analysed monthly, and results published in annual quality reports.
There is no serious argument that Dubai’s water is bad at the point of production. It is held to a standard that many countries with abundant fresh water do not match.
What desalination means for the mineral argument
Here is where an entire genre of water filter advertising falls apart in the UAE.
You will have seen claims that a filter “preserves the healthy minerals in your water”, or the mirror image, that reverse osmosis “strips your water of essential minerals”. Both arguments were written for countries where tap water comes from springs, rivers and aquifers, and arrives carrying dissolved calcium and magnesium picked up from rock.
That is not this water. Desalination removes essentially everything, minerals included, at the plant — long before it reaches any filter in your kitchen. Pure desalinated water is also slightly acidic and would corrode the pipes it travels through, so a controlled amount of mineral content and alkalinity is added back during post-treatment purely to make the water chemically stable and safe to distribute.
So the mineral debate, as it is usually conducted, simply does not apply here. There is no rich mineral profile in your tap for a filter to protect or destroy. The amounts involved either way are small next to what comes from food. If somebody selling you a system here leans hard on the mineral argument, they are reciting a European script without checking whether it describes the country they are standing in.
Plant to glass: the part that actually matters
Now the honest pivot, and it is the whole point of this article.
The water leaving the desalination plant is not the water arriving in your kitchen. Between the two lies a journey, and the journey is where the real questions live.
The water travels a long way through a distribution network of pipes of varying ages. Then, in most buildings here — villas included — it does not go straight to your tap. It goes into a storage tank on or near the building, and sits there until you use it.
Chlorine is added to protect the water across that journey, and it is doing a genuinely important job. It is also the reason so many people say their tap water tastes and smells of a swimming pool, and the reason plenty of them drink less water than they should as a result.
The tank is the bigger variable. Cleaning it is the responsibility of the building owner or the facility manager, not of DEWA. Dubai Municipality sets clear expectations — potable water tanks are to be cleaned and disinfected by a Municipality-approved contractor at least twice a year, more often for higher-risk premises such as hotels, schools and labour accommodation, and proper cleaning means draining, scrubbing, inspection and disinfection rather than a rinse.
The rules are sound. What varies is how consistently they are followed and how well the work is done, across tens of thousands of buildings with tens of thousands of different managers. Most residents have no idea when their tank was last opened, and no practical way to find out.
The tank is also why the water runs warm. A storage tank baking in the sun all day delivers hot water to a cold tap in summer, which we have explained in more detail separately.
The honest reason people filter here
It is not because the source is bad. The source is excellent, and pretending otherwise would be scaremongering about one of the better-run water utilities in the region.
It is because of the gap between the plant and the glass — chlorine added deliberately for a journey that ends at your tap, pipework of unknown age, and a storage tank whose maintenance is somebody else’s job. A filter at the point of use is simply the last stage of treatment, sited where you can actually see it, in the one place where you have control.
That is a smaller claim than most of this industry makes. It is also the true one, and it is enough. Filtering at the tap deals with chlorine taste and odour, sediment picked up along the way, and — depending on the system — a great deal more besides.
If you want to think it through for your own home, our guide to choosing a system works through the questions in order. And since a filter is only as good as its upkeep, our maintenance plans explain how the cartridges get changed on schedule rather than whenever somebody remembers.