What each number adds
A 3-in-1 tap gives boiling, hot and cold water from one spout. A 4-in-1 adds filtered drinking water, normally on its own channel next to the boiling one. A 5-in-1 or 6-in-1 hub adds chilled and sparkling water, which needs a chiller and a CO2 cylinder under the sink. Each step adds a function you may not use, so the useful question is which functions you will use every day.
The 3-in-1 class runs from 299 to 2071 RRP with tanks of 2.4 to 4 litres. 1 of the 4 already lists filtered water in our data, so the label undersells it. The 4-in-1 class runs from 399 to 1249 with tanks of 2.4 to 7 litres, and all of them carry a filter. The sparkling hubs run from 2199 to 2599.
What it costs in tank, filter and space
The tank is the first cost. A boiling tap keeps a tank at temperature all day, and the standby draw in the model rows ranges from 9 to 30 watts on the 3-in-1 taps and 11 to 18 watts on the 4-in-1 taps, up to 33 watts on a hub that also chills. At 27p per kWh, the tariff our running cost calculator uses, standby alone comes to about £21 to £71 a year for a 3-in-1, £26 to £43 for a 4-in-1 and £78 for a hub. Not every model states a figure, so treat these as the range of the ones that do.
The filter is the second cost. A 4-in-1 needs a cartridge, and the interval in our rows is 6 months. That is a recurring purchase on top of the RRP, and the filter cost calculator turns the interval and a cartridge price you enter into a yearly figure. We do not quote a cartridge price here because the model rows do not hold one. The filter guide lists the filter type and interval per tap.
Space is the third. A 3-in-1 or 4-in-1 puts one tank in the sink cabinet. A sparkling hub needs a larger unit that holds the chiller, the filter and a CO2 cylinder, so measure the cabinet first. The sparkling water tap guide gives the unit sizes and the standby comparison for the hubs.
Which class to buy
Buy a 3-in-1 if you want the kettle off the worktop and you already drink tap water or run a jug filter. You avoid the cartridge and pay the least. Buy a 4-in-1 if you want filtered water from the same spout and accept the cartridge as a running cost; the 4-in-1 ranking and the filtered water ranking compare the options. Buy a sparkling hub only if you would otherwise buy fizzy water, because it is the largest install and the largest purchase.
The labels also stretch. Some brands count a feature the others do not, and a 3-in-1 can already include a filter. Check the function list and the maximum temperature on the model page, because 98°C and 100°C are different products under the same number. Our 3-in-1 guide goes through the 3-in-1 class in detail.