The best 4-in-1 boiling water tap for a London kitchen gives you boiling, hot, cold and filtered water from one tap. It should also fit your cupboard, have proper safety features, and come with professional installation. One option that ticks these boxes is the QETTLE Original 4-in-1, which London Water Filter lists at £1,299 (reduced from £1,390), installed and tested, with a choice of 2L, 4L or 7L boiler.
This guide covers what to look for, how the tap works, what it costs to run, and who should pick something different.
What Is a 4-in-1 Boiling Water Tap?
A 4-in-1 boiling water tap delivers boiling, hot, cold and filtered water from a single tap. It replaces your kettle and often your filter jug. A boiler tank under the sink stores the boiling water, and a filter cartridge cleans the water before it is heated or poured.
The four functions are:
- Boiling water for tea, coffee, pasta and sauces
- Hot water for washing up
- Cold water for everyday use
- Filtered water for drinking and cooking
3-in-1 vs 4-in-1 vs 5-in-1: what is the difference?
| Type | Water on offer | Extra under-sink kit | Best for |
|---|---|---|---|
| 3-in-1 | Boiling, hot, cold | Boiler | Kettle replacement on a budget |
| 4-in-1 | Boiling, hot, cold, filtered | Boiler + filter | Households that want filtered drinking water too |
| 5-in-1 | Boiling, hot, cold, filtered chilled and sparkling | Boiler + chiller/carbonator | People who want chilled and fizzy water |
A 4-in-1 is often the middle ground. You get filtered water without paying for the chiller and carbonation hardware of a 5-in-1.
What Makes a 4-in-1 Tap the Best Choice for a London Kitchen?
The best choice fits your home, your household size and your budget, and is installed correctly. London homes vary a lot, from compact flats to large terraces, so one size does not suit everyone.
Check these points:
- True boiling water. Look for a tap that dispenses water at 100°C, not just very hot water.
- Boiler size. Match it to the number of people and how often you make hot drinks.
- Safety. Look for a child-safe handle and a locking step before boiling water flows.
- Filter access and cost. Know how often you must replace the cartridge and what it costs.
- Installation. Professional fitting avoids leaks and warranty problems.
- London water. The area has hard water, so plan for limescale.
- Total cost. Add the tap, boiler, filter, fitting and aftercare together.
Meet the QETTLE Original 4-in-1 Boiling Water Tap
The QETTLE Original is a 4-in-1 tap with an under-sink boiler and filter, supplied by London Water Filter as an installed and tested package. The product page lists a current price of £1,299, down from £1,390.
What is included in the package?
According to the product page, you get:
- The QETTLE Original 4-in-1 tap
- A boiler unit, with capacity depending on the option you choose
- Fittings and adapters
- Professional installation and testing
- A user guide and warranty information
The listing also promises no hidden charges and warranty and aftercare. Ask for the warranty terms in writing before you pay.
Which boiler size should you choose?
A 4L boiler suits most London households. The brand calls it its best seller. QETTLE says a 4L tank gives up to 8 cups of boiling water in one go, and a 7L tank gives up to 14 cups, which suits larger families and small offices. The 2L version holds about 4 cups, going by retailer listings.
| Boiler | Cups in one go (approx.) | Best for |
|---|---|---|
| 2L | About 4 | Singles, couples, small kitchens |
| 4L | Up to 8 | Most families |
| 7L | Up to 14 | Large households, home offices, entertaining |
A bigger boiler means more under-sink space and a higher standby cost. Pick the smallest size that covers your busiest moments, such as a morning rush or a dinner party.
How safe is it?
QETTLE describes a two-stage safety system and a safety clip on its taps. The brand says all its taps come with a safety clip. Retailer listings add a child-safe handle, a boiling-water lock and, on some models, a cool-touch spout. Boiling water is still dangerous. Keep children away from the tap, and ask your installer to show you how the controls work.
How Does a 4-in-1 Boiling Water Tap Work?
Mains water passes through a filter cartridge, then into an under-sink boiler where it is heated to boiling. The tap dispenses it when you operate the safety controls. Hot and cold work like a standard mixer tap.
In more detail:
- Water enters through the under-sink connections.
- The filter cartridge treats it first. QETTLE’s cartridge is called the Q08.
- The boiler heats and stores the water at 100°C.
- The tap releases boiling water only after you complete the safety steps.
- The boiler refills. Retailer listings say a drained 2L tank refills in around 10 minutes.
How Much Does a 4-in-1 Boiling Water Tap Cost in London?
For this package, the price is £1,299 with installation and testing included. Always check which boiler size that price covers, because the page lists three options.
What does it cost to run?
There are two running costs: electricity and upkeep.
Electricity. QETTLE states that its 4L boiler uses 39W on standby. Here is a simple example. At 39W, the boiler uses about 0.94 kWh a day. At an example price of 25p per kWh, that is roughly 23p a day, or about £85 a year at most. Your real cost depends on your tariff and how much the boiler actually heats. Some premium systems use vacuum-insulated tanks with lower standby power, but they cost more to buy.
Upkeep. QETTLE advises replacing the filter cartridge twice a year and deep cleaning the boiler tank once a year. Ask for the filter price up front, and consider a service plan.
Why compare the full package price?
A tap on its own is not the whole system. You also need a boiler, a filter, fittings and a fitter. A single installed price makes quotes easier to compare and shows the real total.
Is a 4-in-1 Boiling Water Tap Suitable for London Homes?
Usually yes, but check your plumbing and space first. London kitchens range from tight flats to large extensions, so a pre-install check matters.
What should be checked before installation?
- Tap hole. Retailer listings for QETTLE Original taps give a 35 mm single hole. Confirm this for your model.
- Water pressure. Retailer listings give a minimum pressure of 1.5 bar, and one gives a maximum of 5 bar. Confirm both with the supplier.
- Under-sink space. Measure the cupboard and ask for the boiler and filter dimensions. Remember pipes and waste fittings.
- A nearby socket. The boiler needs mains power.
- Compliance. Installations should meet the Water Supply (Water Fittings) Regulations 1999. A professional fitter will know this.
The product page asks you to get in touch before ordering if you are unsure about your setup, and the team runs a showroom at 21 Upper Tulse Hill, SW2 2SD.
Does London’s hard water matter?
Yes, expect limescale. Thames Water says water across its region is hard because it runs through chalk and limestone, and it rates 200–300 mg/l as hard and above 300 as very hard. A filter improves taste and cuts some contaminants, but it is not the same as a softener. Plan on regular cleaning, and follow the boiler-cleaning schedule above. If you also have a whole-house softener, ask your installer how it affects the tap.
Who Is the QETTLE Original Best For, and Who Should Look Elsewhere?
It suits people who want filtered boiling water without paying for chilled and sparkling extras.
A good fit if you:
- Want to ditch the kettle and the filter jug
- Prefer one supplier for the tap and the fitting
- Have room under the sink for a boiler and filter
- Want a choice of boiler sizes
Think twice if you:
- Want chilled or sparkling water from the tap (look at 5-in-1 systems instead)
- Have a very small cupboard with no spare room
- Only want boiling water and nothing else (a 3-in-1 may be enough)
- Dislike routine filter changes
Common Mistakes to Avoid
- Buying the biggest boiler “just in case.” It takes more space and uses more standby power.
- Ignoring cupboard measurements. Always measure before you order.
- Skipping filter costs. The cartridge is a recurring expense.
- Assuming a filter removes limescale. It does not soften water.
- Comparing tap-only prices. Compare installed totals.
- Treating boiling water casually. Teach everyone in the house how the safety steps work.
Frequently Asked Questions
1. What is the best 4-in-1 boiling water tap for a London kitchen?
The best one fits your cupboard and household and comes professionally installed. The QETTLE Original 4-in-1 is a strong option, available in 2L, 4L and 7L boiler sizes.
2. What does 4-in-1 mean?
It means boiling, hot, cold and filtered water from one tap.
3. Does the price include installation?
Yes. The product page states professional installation and testing are included.
4. Which boiler size should I choose?
A 4L boiler suits most families. Choose 2L for one or two people, and 7L for larger households.
5. Is a boiling water tap safe for children?
QETTLE describes a two-stage safety system and safety clip, and retailers mention a child-safe handle. Adult supervision still matters.
6. How often do I replace the filter?
QETTLE advises twice a year, with a boiler deep clean once a year.
7. How much electricity does it use?
QETTLE states the 4L boiler uses 39W on standby. Real running costs depend on your tariff and use.
8. Will it work with London’s hard water?
Yes, but limescale builds up over time. A filter does not soften water, so expect regular cleaning.
9. Can it be installed in an existing kitchen?
Often, yes, if the tap hole, pressure, power and cupboard space suit. A pre-install check will confirm.
10. Does it give sparkling or chilled water?
No. A 4-in-1 gives boiling, hot, cold and filtered water. Chilled and sparkling water need a 5-in-1 system.
Ready to Check Whether It Fits Your Kitchen?
If a filtered boiling water tap suits your home, take a look at the QETTLE Original 4-in-1 Instant Boiling Water Tap, installed and tested. Message the team with your cupboard size and preferred boiler size, or visit the London showroom to see it first.
