Reviewed by the Quel Tap product team. Last updated on: October 2026.
A kitchen tap used to do two things: provide hot and cold water. Kitchens are increasingly asking more of it than that, and if you’ve started comparing models, you’ll have noticed the terminology stacks up fast: 4-in-1, 5-in-1, 6-in-1, filtered, boiler size. It’s easy to feel you need a plumbing background just to compare two products, but you don’t.
Underneath the labels, there are really only a handful of decisions: what the tap dispenses, whether it filters what it dispenses, and how much water the boiler keeps ready at any one time. This guide works through each in plain terms, so the spec sheet on any Quel Tap model makes sense at a glance.
How does a boiling water tap work?
Most boiling water taps are fed by a small boiler, usually fitted in the cupboard under the sink, which heats and holds water so it’s typically ready for use within a few seconds. Quel Tap uses a vented, non-pressurised boiler design, which allows a small, controlled amount of expansion as the water heats rather than sealing the boiler tank under pressure. In practice, this generally means a steadier, more controlled pour at the tap, without the surges or spitting that can sometimes affect pressurised systems. Every Quel Tap boiler heats filtered water to up to 98°C and holds it ready to dispense on demand.
It’s worth being precise about what’s filtered and what isn’t:
- The filtered supply and the standard hot and cold supply are two separate lines into the tap, not one shared line.
- Filtered water feeds the boiling and filtered cold functions, plus chilled and sparkling on the models that offer them.
- Standard hot and cold water, drawn straight from your existing supply, handles the tap’s everyday duties of washing up, rinsing vegetables, filling a pan and general kitchen cleaning, exactly as a normal kitchen tap would.
That last point gets missed surprisingly often. A boiling water tap isn’t a specialist drinks tap that sits alongside your real one. It is your kitchen tap, doing everything the old one did, and more.
4-in-1 boiling water taps
A 4-in-1 tap is the foundation of the Quel Tap range: filtered boiling water, filtered cold water, and standard hot and cold water from one fixture, with filtration included as standard rather than treated as an upgrade. Standard prices start from £499.99 inc. VAT for the Quel Classic, though promotional pricing may be available from time to time and can vary.
For most kitchens, this is the natural middle ground: one fixture replacing the kitchen tap, filtration already accounted for, and the kettle and filter jug both retired.
The value here tends to go beyond the price tag or the running cost. A 4-in-1 tap saves the pockets of time spent waiting for a kettle throughout the day. It’s versatile, with instant boiling water working just as well for cooking pasta or vegetables and topping up a stockpot as it does for a cup of tea, while the filtered cold side gives a standing supply of drinking water without a jug taking up fridge space.
5-in-1 boiling water taps
A 5-in-1 tap builds on the foundation of a 4-in-1 tap and adds chilled filtered sparkling water as a separate setting. It suits households whose motivation isn’t only to replace the kettle and the filter jug, but also the sparkling water machine or the crate of bottles taking up floor space. The Quel Digital Fizz sits here, at a standard price of £1,249.99 inc. VAT, again subject to any promotions running at the time.
Worth knowing before you commit: sparkling function means a CO₂ cylinder and regulator, bought separately, living in the cupboard alongside the boiler.
6-in-1 boiling water taps
A 6-in-1 tap has everything the 5-in-1 offers, including filtered chilled water and sparkling water, and adds filtered ambient water on top. This is the option for a kitchen that wants to retire the kettle, the filter jug and the sparkling water maker in one go, with filtered ambient water sitting alongside it. The Quel Ultimo covers this, at a standard price of £1,369.99 inc. VAT, promotions permitting.
4-in-1 vs 5-in-1 vs 6-in-1 at a glance
| Tap Features | 4-in-1 | 5-in-1 | 6-in-1 |
|---|---|---|---|
| Filtered boiling water (up to 98°C) | Yes | Yes | Yes |
| Filtered cold water | Yes | No | Yes |
| Filtered sparkling water | No | Yes | Yes |
| Filtered chilled water | No | Yes | Yes |
| Standard hot and cold water | Yes | Yes | Yes |
| Quel Tap models | Quel Classic, Quel Digital, Quel Ultra, Quel Ultra Plus | Quel Digital Fizz | Quel Ultimo |
| CO₂ cylinder needed | No | Yes | Yes |
| Standard price from | £499.99 | £1,249.99 | £1,369.99 |
| Best suited to | Replacing the kettle and filter jug | Also replacing a sparkling water maker | Replacing all three, with a dedicated chilled setting |
Standard prices shown inc. VAT and correct at the time of writing. Promotional pricing may be available and can vary.
Filtered vs unfiltered water: what filtration actually changes
Boiling and filtering aren’t the same thing and don’t do the same job. Boiling water is generally effective at dealing with bacteria and viruses, but it doesn’t remove dissolved substances like chlorine, limescale minerals, or the taste and odour some households notice in their local supply. Filtration is a separate process, aimed at taste and clarity rather than sterilisation.
It’s worth saying plainly: UK tap water is already safe to drink, and held to strict standards. The Drinking Water Inspectorate’s most recent annual report puts English public water supply compliance at 99.98% against microbiological standards and 99.95% against chemical standards in England. Filtration on a kitchen tap is about how the water tastes and feels, not about making it safe to drink.
Every Quel Tap uses a nano-phosphate filter cartridge, fitted to the filtered supply line. It helps reduce common impurities and will protect the boiler against limescale build-up. Filters should be replaced around every 6 months.
Boiler size: the detail that affects everyday use most
Every Quel Tap relies on an under-sink boiler, and boiler size (sometimes referred to as tank size) is one of the most overlooked specs when comparing boiling tap models. It directly affects how the tap copes with a busy kitchen.
- A smaller boiler generally suits lighter, occasional use, and will typically need a short pause to reheat if drawn on repeatedly in quick succession.
- A larger boiler holds more water at temperature, so it tends to cope more comfortably with a larger family kitchen: a few cups of tea back to back, water for pasta, and a top-up for whatever is asked of the tap next.
There isn’t a single correct answer. It’s a question of how the tap will actually be used day to day, and it’s worth checking this figure specifically rather than assuming all boilers perform the same. Full product specifications for each model are listed on the boiling water taps range page.
Are boiling water taps worth it?
That depends on what you’re weighing, and it’s fairer to look at more than the electricity bill.
1. On energy and habit
A 2013 Energy Saving Trust Foundation study found that three-quarters of UK households overfill the kettle every time they use it, wasting an estimated £68 million in energy each year between them. A tap that keeps water ready removes most of that guesswork. From our own research, a 2.4 litre Quel Tap boiler typically draws around 0.75 kWh over 24 hours to hold water at temperature, which is worth weighing against how your household actually uses hot water rather than being assumed as an automatic saving.
2. On time
A kettle can take two to three minutes to boil, and that wait repeats with every hot drink. Over several drinks a day, those minutes add up, and a boiling water tap gives that time back. This everyday convenience is something Quel Tap owners regularly praise on Trustpilot.
3. On versatility
One fixture covering tea and coffee, blanching vegetables, filling pans, filtered drinking water, and washing up. On 5-in-1 and 6-in-1 models, chilled and sparkling water as well.
4. On plastic
The Greater London Authority puts UK plastic water bottle purchases at around 7.7 billion a year. A filtered tap won’t solve that alone, but for a household reaching for one bottle a day out of habit rather than necessity, swapping it for filtered tap water works out at roughly 365 fewer bottles a year.
How to choose the right type for your kitchen
The right one comes down to what’s actually cluttering your routine right now:
- Replacing the kettle and the filter jug: a 4-in-1 covers it.
- Also wanting chilled and sparkling water, whether to replace a sparkling water maker or to buy less bottled sparkling water: step up to a 5-in-1.
- Wanting filtered ambient water on top of everything the 5-in-1 offers: choose a 6-in-1.
If you’re mid-renovation, this is a convenient moment to choose a tap, though you don’t need to plan the whole project around it. Every Quel Tap model will fit standard tap holes, so the worktop and sink cutouts can go ahead as normal. The only extras to build in are space in the cupboard below for the boiler and filter, and a nearby socket, which are simple to include while the cupboard layout is still open.
On cover, the detail matters more than the headline number. As standard, every Quel Tap comes with a 5-year warranty on the tap and a 2-year warranty on the boiler. That boiler cover can be extended to 5 years for an additional cost, provided you register within 30 days of purchase and keep to 6-monthly filter replacements using genuine filters. Standard and extended terms aren’t the same thing, and that’s worth checking carefully on any tap you compare, whatever the brand.
If something does go wrong, or you simply want to talk it through before ordering, our support team is UK-based and reachable by phone or email.
Water, beautifully controlled, however many ways you ask for it.
Ready to see them side by side?
Every model in the range, from the entry-level 4-in-1 through to the 6-in-1 Quel Ultimo, includes filtered water as standard, and most customers fit their own in 1 to 2 hours. Explore the full range of Quel Tap boiling water taps to find the fit for your kitchen.
Frequently Asked Questions (FAQs)
Is filtered water from a boiling water tap safer than tap water?
UK tap water already meets strict national standards, so filtration isn’t primarily about safety. It’s about taste, clarity and reducing the chlorine or mineral character some households notice in their local supply.
Do I need a plumber to fit a boiling water tap?
Most customers fit their own within 1 to 2 hours using the written and video installation guidance supplied. A qualified plumber can carry out the work if you’d prefer, and it’s worth considering if your under-sink pipework is awkward or you don’t have a socket in the cupboard yet.
Can I put a boiling water tap in an existing kitchen, or only a new one?
Both. Every Quel Tap model will fit in standard tap holes, so a new kitchen isn’t required. What they do need is space in the cupboard below for the boiler and filter, plus the chiller on our 5-in-1 or 6-in-1 models, and a nearby socket.
What happens if I don’t replace my filter on schedule?
Beyond affecting water taste and boiler performance, 6-monthly replacement with genuine filters is a condition of the 5-year warranty, so missing the schedule can affect your cover as well as your water.
Does a boiling water tap still give normal hot and cold water?
Yes. The standard hot and cold supply runs on its own separate line and handles everything a normal kitchen tap does, including washing up and rinsing. The filtered and boiling functions sit alongside it rather than replacing it.