Cloudy ice is one of the most common small complaints in a UAE kitchen, and it is almost never a sign that anything is wrong with the water. The white core in the middle of a tray cube is mostly trapped air. A smaller part of it is whatever was dissolved in the water before it froze, and a much larger part than most people expect is simply the direction the ice grew in.
Which leads to an answer worth giving before the explanation. Filtered water will change how your ice tastes, and it will meaningfully extend the life of an ice machine, but it will not on its own produce the clear cubes you see in a bar. Anyone promising clear ice from a filter is overstating what filtration does. The rest of this article sets out why, because the mechanism also tells you what would actually work.
Why the middle of a cube goes white
Water in a tray freezes from the outside in. The faces touching cold air and cold plastic reach freezing point first, so a shell forms around the outside of each cube and the freeze front travels inwards from every direction at once.
Ice is a highly ordered crystal, and as it forms it will not take much else into its structure. Dissolved gas — ordinarily air, which is present in every glass of water anyone has ever poured — is pushed ahead of the advancing front rather than being frozen in place. So is anything dissolved in the water. Both get driven into the shrinking pocket of liquid still unfrozen at the centre of the cube.
That pocket has nowhere to vent, because the shell has already closed around it. When it finally freezes, the gas comes out of solution as a mass of microscopic bubbles, locked where they formed. Every bubble is a surface that scatters light, and enough of them together read to the eye as white. The cloud sits in the middle because the middle is the last part to freeze, which is also why the outside of a tray cube is usually perfectly clear.
Where dissolved solids come into it
They contribute, but less than the folklore suggests, and the clearest evidence for that is local. In Dubai and Abu Dhabi the supply is desalinated and arrives with very little dissolved in it, and ice made from it still comes out white in the middle. If dissolved content were the main cause, ice here would be noticeably clearer than ice made in a groundwater region, and it is not.
Where the dissolved load is genuinely higher — Sharjah, Ras Al Khaimah, Fujairah and Umm Al Quwain draw more groundwater into their supply — cubes can look denser through the centre and occasionally leave a faint residue in the bottom of a glass as they melt. The differences between the two are set out in our piece on how northern emirates water compares with Dubai. Even there, the air is doing most of the work.
Why bar ice looks different
Two entirely different processes are behind clear ice, and neither of them is a filter.
Directional freezing
If water can only freeze from one direction, the physics stops working against you. Insulate a container on every side but the top, put it in the freezer, and the freeze front travels steadily downwards in a single direction. Air and dissolved material are pushed ahead of it rather than being surrounded and sealed in, so they end up concentrated in the last portion at the bottom, which stays cloudy. That portion is cut off and discarded, and what remains above it is genuinely clear ice.
This is what serious cocktail bars do, and anyone can do it at home with a small insulated cool box and a serrated knife. It is slow, it wastes the bottom third of everything you freeze, and it produces a block to be cut rather than cubes to be tipped out. That trade-off is the entire reason ordinary trays are not made this way.
Commercial ice machines
A commercial machine does not fill a mould and freeze it. Water is pumped continuously over a chilled plate, and ice builds on that plate in thin layers out of flowing water. Because the water is moving, gas coming out of solution escapes into the stream instead of being trapped, and dissolved material is left behind in the water still circulating, which is flushed to drain periodically rather than being frozen into the cube.
The result is hard, dense, slow-melting ice, and it is clear because of the way the machine builds it. The same machine fed straight from the tap still makes clear ice. Filtration is doing something quite different there, which is the next point.
What filtered water genuinely changes: taste
Ice tastes of two things — the water it was made from, and the freezer it has been sitting in.
The water side is where filtration earns its place. Tap water across the country carries chlorine, kept in the supply deliberately to protect it on the way to your building, and it passes straight through into ice. It is easy to overlook in a glass and much more obvious in a spirit, a soft drink or a jug of iced water where the ice slowly dilutes everything around it. Carbon filtration deals with chlorine well, as covered in our article on chlorine in Dubai tap water, and it is the one change most people notice in their ice within a day.
The freezer side no filter can help with. Ice readily picks up volatile compounds from whatever is stored near it, so cubes left in an open tray for weeks will taste of the freezer however good the water was. If your ice tastes stale rather than chemical, the answer is a covered container and making it more often.
If you have an ice machine, filter it — for the machine
Here the case is genuinely strong, and it has nothing to do with how the cubes look.
An ice machine takes water in and removes most of it as ice. Everything that was in that water and did not become ice stays behind, concentrated, on the evaporator plate and in the sump. Over months that accumulates on exactly the surfaces the machine relies on to move heat, so it makes ice more slowly, runs longer for the same output, and eventually stops keeping up on the days you need it most.
Two things do the damage in a UAE building:
- Sediment. Grit, rust flakes off older pipework and sludge out of the building’s storage tank all reach the machine’s pump, its inlet valve and its narrow internal passages. It is a common failure mode and an entirely preventable one.
- Dissolved mineral content. A real problem in the northern emirates and a slower one in Dubai and Abu Dhabi, where the supply carries very little. The same scaling that shows up on kettles and around kitchen fittings, the subject of our piece on limescale in Dubai kitchens, happens inside an ice machine where nobody can see it.
The arithmetic is not close. A cartridge costs a fraction of a descaling visit and a small fraction of a replacement machine, and a machine that stops on a Friday evening in a busy venue costs more than either. For restaurants and cafés the wider picture is in water filtration for restaurants. A small counter-top ice maker at home follows the same logic in miniature: feed it filtered water and it will last longer, though it will still make cloudy cubes.
Things that are supposed to help and mostly do not
- Boiling the water first. There is real physics behind this, since boiling drives dissolved gas out of water. But a tray still freezes from all sides, and gas redissolves as the water cools, so what is left ends up trapped in the middle as usual. Cooled boiled water gives a slightly clearer cube, not a clear one.
- Using reverse osmosis or distilled water. It removes dissolved solids and does nothing about air, and water standing in an open tray takes air back up from the room before it freezes. The cube still clouds.
- Turning the freezer colder. Faster freezing traps more gas rather than less, so this makes cloudiness marginally worse.
- Bottled water. Same air, same tray, same result, with the cost and the plastic on top.
One thing worth separating out
People who make a great deal of ice are often really trying to solve a different problem, which is that water arriving in a UAE kitchen is warm all year round and no amount of filtration changes that. A filter does not make water cold. That is a chiller’s job, a separate machine with its own cabinet space, its own power socket and at least two hours more work on the day of fitting. The options are compared in how to get cold water in Dubai, and for most households a chiller is a better answer to a warm tap than a freezer full of trays.
The practical version
Filter your water because it makes your ice taste of nothing, and because an ice machine fed filtered water lasts appreciably longer before anyone has to open it. Do not filter it expecting clear cubes. Clarity comes from freezing in one direction, which means either an insulated container and some patience, or a commercial machine that builds its ice in layers. Anyone unsure which drinking system suits their kitchen and their emirate can work through the product finder, which asks about both before it recommends anything.