What an instant hot water tap is
The tank is a small insulated boiler that sits in the sink cabinet and holds water at temperature until you need it. The tap on the worktop is only the outlet. In our model library the tanks hold 2 to 7 litres and the water leaves the spout at 98 to 100°C, depending on the model.
Some brands call the result boiling water and publish 100°C. Others say steaming hot and stop at 98°C. A few add a thermostat: the Hanstrom Saxan 4-in-1 lists presets from 75 to 98°C, which suits a cup of green tea. Check the temperature in the spec table before you compare two taps, because the two words describe slightly different products.
3-in-1, 4-in-1 and 5-in-1 explained
The number counts the kinds of water that come out of one spout. Brands do not count the same way.
Read the list of functions, not the number.
A 3-in-1 gives boiling, hot and cold water. The Franke Maris Water Hub 3-in-1 and the Hanstrom Ume 3-in-1 are examples. The boiling water comes from the tank.
A 4-in-1 adds filtered water. On most of the range that means a separate filtered drinking channel next to the boiling one: the Qettle Original 4-in-1, the Fohen Focetti Pro 4-in-1 and the Hanstrom Saxan 4-in-1 all work like that. Our library notes that the Franke Maris Electronic is the only Franke you can upgrade to a 4-in-1 later.
Beyond four, the label stops being a safe guide. The Franke Mythos Water Hub 6-in-1 delivers boiling, hot, cold, filtered, chilled and sparkling water. The Franke Mythos Water Hub 5-in-1 is the same hub without the boiler, so it has no boiling water at all. If boiling water is the reason you are shopping, the 5-in-1 is the wrong tap.
A fourth group is the dedicated tap, which only dispenses hot water and sits next to your existing mixer. The InSinkErator GN1100 and the Quooker Nordic single taps are built that way. You keep your current mixer and add the hot water spout beside it.
What it costs
The price of the tap is the first number and rarely the last one. Across the active taps in our library the recommended retail prices run from £299 to £3,693. The hubs with chilled and sparkling water sit at the top of that range.
We show recommended retail prices rather than shop prices. Amazon's affiliate rules only allow live prices through their own API, so our offer links carry no stored price, and we do not copy a figure that goes stale within days. Retailer offers appear on a model page only when they were checked in the last 45 days, with the date shown.
Two running costs come on top. The tank keeps its water hot all day, so it draws a small amount of power while idle, and filtered models need a replacement cartridge on a schedule. The running cost calculator works both out from the tap's wattage and your tariff.
Fitting one in broad terms
The tank needs a place in the sink cabinet, a cold water feed and a power socket nearby, and a filtered model needs room for a cartridge as well. Measure the cabinet against the tank dimensions in the spec, and check the manufacturer's installation guide for the supply and socket requirements before you order. If you want an installer to do it, use our installer finder. The installation cost estimator gives a rough range before you ask for quotes.
Mistakes when choosing
- Choosing by the "-in-1" number. Read the list of functions.
- Ignoring the tank size. A 2.4 litre tank holds fewer mugs than a 7 litre one, and the Qettle Signature Modern with the 7 litre boiler lists about 14 cups per fill. Match the tank to the number of people in your household.
- Leaving the filter out of the budget. The cartridge is a recurring purchase.
- Comparing prices from different dates. Compare recommended retail prices with recommended retail prices, and shop prices with shop prices checked on the same day.
- Skipping the cabinet measurement. A tank that does not fit the cabinet is the most common reason a tap order goes wrong.