Sparkling water makers only have one job: to blow carbon dioxide into tap water. Four out of seven sparkling water makers tested are really good at this. They make fizzy soda and achieve good Stiftung Warentest quality ratings. Others bubble a little weaker. And one of the sparkling water makers tested is inadequate: it often overflows and then stops working altogether...

Sparkling water makers are practical and convenient - especially compared to lugging water around. Anyone who likes fizzy water is guaranteed to be happy with the test winner from HappyMix. Sodastream's "E-Duo" is particularly convenient, but is the only device tested that requires a power connection.

... We also had the impression that, despite the promised compatibility with cylinders from other manufacturers, the system got more out of the brand's own cartridges than with products from competitors. However, as friends of high-foaming drinking pleasures, we preferred to return to industrially inflated mineral water after a few weeks.