How a sparkling water tap works
The tap on the worktop is the small part. Under the sink sits a unit that holds the chiller, the filter cartridge and a CO2 cylinder, and on the boiling model the boiler too. The unit filters, chills and carbonates the water before it reaches the spout. That is why a sparkling tap is an install job and not a swap: it needs a hole in the worktop or sink, space under the sink for the unit, a power socket and a supply at the tap.
Franke Mythos Water Hub 5-in-1: a 2.2 litre chiller and no boiler, filtered through Pro M Connect: active carbon + ion-exchange resin with a 12 month filter interval. The tap needs a 35 mm hole and fits a worktop up to 50 mm thick.
Franke Mythos Water Hub 6-in-1: a chiller and a 4 litre boiler, in an under-sink unit of 440 by 200 by 495 mm (width, depth, height), filtered through Pro M Connect: active carbon + ion-exchange resin with a 12 month filter interval. The tap needs a 35 mm hole and fits a worktop up to 50 mm thick.
All-in-one or no boiler
The choice in our data is between Franke Mythos Water Hub 5-in-1 and Franke Mythos Water Hub 6-in-1. The difference is the boiler: £400 more at RRP, and a standby draw of 33 watts for the one that keeps a tank at boiling point.
What the model pages say for and against
Franke Mythos Water Hub 5-in-1: in its favour, sparkling, chilled and filtered water from one tap without paying for a boiling tank you would not use. Against it, no boiling water at all, so the kettle stays on the worktop. It carries a 2 year warranty.
Franke Mythos Water Hub 6-in-1: in its favour, six functions from one tap: boiling, chilled, ambient and sparkling plus hot and cold mains. Against it, sparkling water is held as 0.6 litres in the chiller and runs to 2.8 litres before it has to catch up, with a CO2 cylinder to replace. It carries a 2 year warranty.
The full lists of pros and cons, the finishes and the sources behind each number are on the model pages. We rank no sparkling tap above another here: with two taps in the library the decision is whether you want a boiler, and the section above shows what that costs.
What to check before you buy
Measure the space under your sink against the unit sizes above, and check the tap hole size and the worktop thickness against your sink. Plan for a power socket under the sink. Installation is not in the RRP; our installation cost estimator puts a simple swap at around £130 to £200. A sparkling unit is not a simple swap, so ask an installer for a quote.
For a boiling tap without carbonation, the 4-in-1 guide ranks the options, and Quooker vs Franke puts the two brands side by side. Filter types and replacement intervals for every tap are in the filter guide.