If the cold tap in your kitchen runs warm in August and you have been looking at water filters hoping one will fix it, the first thing worth knowing is that none of them will. Filtration and cooling are two separate jobs done by two different machines. A filter removes things from water; it has no thermal function at all, so water leaves a basic under-sink or counter-top system at exactly the temperature it entered.
What produces cold water at a kitchen tap is a chiller: a small refrigeration unit that lives in the cabinet, takes water from the filtered line and holds a chilled reserve ready to pour. This article covers why the supply is warm here in the first place, what a chiller does and does not do, how it compares with the two alternatives most households already have, what fitting one actually involves, and — the part rarely written down — who genuinely does not need one.
Why the cold tap is warm all year
This is not a fault with your plumbing and it is not seasonal in the way people expect. It is a consequence of how water reaches a building in this country.
Water arrives at your property and then waits. In a tower it waits in tanks and risers; in a villa it usually waits in a tank on the property itself, frequently in the open. Ambient temperatures here stay high for months at a stretch, and surfaces exposed to the sun are hotter still. Water absorbs heat readily and sheds it slowly, so a tank of several hundred litres that warms through a July afternoon does not cool overnight — there is nothing to cool it.
Two things follow. The cold tap is fed from a reservoir that has been heated in storage, so it is warm at the point it leaves the pipe rather than picking up heat on the way. And running the tap does not help, because behind the water in the pipe is more water at the same temperature. The mechanism is set out in more detail in our piece on why Dubai tap water is warm.
What a chiller does that a filter cannot
A chiller is a compressor, a refrigerant circuit and a small insulated reservoir. Water is drawn from the filtered line into that reservoir, cooled, and held there so the first glass is properly cold rather than arriving cold eventually.
That reserve is the part worth understanding, because it explains the one limitation an under-sink chiller has. The unit cools a fixed volume at a time and then catches up. Draw a couple of glasses and you will not notice it. Fill a large jug and several bottles in quick succession and the last of it comes out cooler than the tap but not cold, and the machine needs a little time before it is back to normal. This is normal behaviour rather than a fault, and it is worth knowing before the first dinner party rather than after.
What a chiller does not do is filter. On a combined installation the filtration is being done by the cartridges and the cooling by the chiller, in the same cabinet, as two independent pieces of equipment. If somebody tells you a filter will deliver cold water, they are either being careless or selling on a promise the machine cannot keep — a point covered from the other direction in our guide to under-sink filters.
Chiller, fridge dispenser or bottled cooler
Most households considering a chiller are already doing one of the other two, so the honest comparison is against what you have rather than against nothing.
The fridge
Keeping a jug or bottles in the fridge costs nothing and works. Its limits are practical rather than technical: it consumes shelf space that a UAE household refilling several times a day feels quickly, there is a wait whenever the jug has just been emptied and refilled, and somebody has to remember. Plumbed fridge dispensers avoid the refilling but tie you to that appliance, they are often fed through a small in-line cartridge with a much shorter service life than a proper drinking system, and when the fridge is replaced the arrangement goes with it.
A chiller is worth considering when the fridge routine has become a chore that keeps failing — the jug is empty when you want it, or the bottles have colonised a shelf you would rather use for food.
The bottled cooler
The five-gallon cooler solves temperature reliably and creates a different set of problems. Somebody has to be home for deliveries, the empties have to be stored, and each bottle has to be lifted onto the machine, which is a real consideration in a household where not everyone can hoist a full one above waist height. There is also the plastic, which for a great many customers is the reason they started looking in the first place. What the running cost of that habit adds up to over a year is set out in our piece on what a UAE family spends on bottled water.
A plumbed chiller replaces all of that with a tap. There is nothing to order, lift or store, and the only recurring task is the cartridge changes the filtration would have needed anyway.
The under-sink chiller
It gives cold water on demand at one tap, out of sight, with no bottles and nothing on the worktop. Against that it occupies cabinet space, needs a socket, uses electricity continuously in the way any refrigeration does, and adds a machine to the kitchen that can eventually need attention. It is a considered purchase rather than an obvious one, which is why the comparison above matters. Specification is on the under-sink chiller page.
What installing one involves
The chiller sits in the cabinet alongside the filtration, plumbed into the line between the filter and the tap so that what it cools has already been filtered. Cold water is then delivered at the dedicated drinking tap on the worktop. Your ordinary mixer is untouched and continues to run warm, because it is fed from the building’s supply exactly as it always was.
On timing, this is worth being precise about because it is frequently understated. An under-sink filter on its own takes 20 to 45 minutes to fit. Adding a chiller adds at least two hours to that. The unit has to be positioned so it can shed the heat it removes, connected into the water line, supplied with power, and then run and checked once it has come down to temperature. It is a morning’s work rather than a quick call, and the general sequence of a fitting visit is described in what happens when a water filter is installed.
Three practical checks are worth making before you order.
- Space. A chiller is a solid box, not a cartridge bank, and it needs clear air around it. A cabinet already holding a waste trap, a filter and the cleaning products may be tighter than it looks. Where the sink unit will not take it, the chiller can often sit in an adjacent cupboard with tubing run between the two.
- A socket. It needs mains power within reach, permanently. Many kitchens have a spare socket under the sink and many do not, and finding out on the day is how an installation becomes two visits.
- Ventilation. Refrigeration works by moving heat out of the water and into the room, so a unit sealed into an airtight space works harder, runs longer and cools less well. A cabinet with a little air movement is worth more than a slightly larger one without.
Who genuinely does not need one
Several households ask about a chiller and would be better served by not buying one, and it is worth saying so plainly.
If the fridge routine already works for you, it works. A jug that gets refilled without anybody minding is a perfectly good solution and there is no argument for spending money to replace it.
If your complaint is the shower rather than the drinking water, this is the wrong machine entirely. An under-sink chiller cools a drinking line at one sink and does nothing for the bathrooms, the washing machine or the garden tap. Cooling the whole property means treating the stored water instead, which is a different installation altogether and is covered in our piece on villa water tank chillers.
If you are on a short tenancy, weigh it up carefully. The unit can be uninstalled and refitted at a new address, but it is a second machine to move and the next kitchen needs the space and the socket as well.
And if you drink very little cold water — plenty of households here do not, particularly those who mostly drink tea and coffee — then this is a machine that will hum away in your cabinet on your behalf for no benefit you will notice.
Living with one
A chiller adds no filtration cartridges of its own, so the maintenance rhythm is unchanged: the drinking system’s cartridges are replaced twice a year and the chiller is checked at the same visits. Every system comes with 12 months of warranty and 12 months of maintenance included, and from year two an active maintenance plan covers the visits and keeps that warranty alive.
The sensible way to decide is to be honest about which problem you have. If it is warm drinking water in the kitchen and the fridge has stopped keeping up, an under-sink chiller answers it directly. If it is the whole property, look at the tank. And if the filter has not been bought yet, decide about the chiller now rather than later — fitting both in one visit is straightforward, and returning to add one afterwards means opening the installation up again.